Remove the memmove call on dns_rbtnode_t structure that contains atomics

Calling the plain memmove on the structure that contains atomic members
triggers following TSAN warning (even when we don't really use the
atomic members in the code):

    WARNING: ThreadSanitizer: data race
      Read of size 8 at 0x000000000001 by thread T1 (mutexes: write M1, write M2):
	#0 memmove <null>
	#1 memmove /usr/include/x86_64-linux-gnu/bits/string_fortified.h:40:10
	#2 deletefromlevel lib/dns/rbt.c:2675:3
	#3 dns_rbt_deletenode lib/dns/rbt.c:2143:2
	#4 delete_node lib/dns/rbtdb.c
	#5 decrement_reference lib/dns/rbtdb.c:2202:4
	#6 prune_tree lib/dns/rbtdb.c:2259:3
	#7 dispatch lib/isc/task.c:1152:7
	#8 run lib/isc/task.c:1344:2

      Previous atomic write of size 8 at 0x000000000001 by thread T2 (mutexes: read M3):
	#0 __tsan_atomic64_fetch_sub <null>
	#1 decrement_reference lib/dns/rbtdb.c:2103:7
	#2 detachnode lib/dns/rbtdb.c:5440:6
	#3 dns_db_detachnode lib/dns/db.c:588:2
	#4 qctx_clean lib/ns/query.c:5104:3
	#5 ns_query_done lib/ns/query.c:10868:2
	#6 query_sign_nodata lib/ns/query.c
	#7 query_nodata lib/ns/query.c:8438:11
	#8 query_gotanswer lib/ns/query.c
	#9 query_lookup lib/ns/query.c:5624:10
	#10 ns__query_start lib/ns/query.c:5500:10
	#11 query_setup lib/ns/query.c:5224:11
	#12 ns_query_start lib/ns/query.c:11357:8
	#13 ns__client_request lib/ns/client.c:2166:3
	#14 udp_recv_cb lib/isc/netmgr/udp.c:414:2
	#15 uv__udp_recvmsg /home/ondrej/Projects/tsan/libuv/src/unix/udp.c
	#16 uv__udp_io /home/ondrej/Projects/tsan/libuv/src/unix/udp.c:180:5
	#17 uv__io_poll /home/ondrej/Projects/tsan/libuv/src/unix/linux-core.c:461:11
	#18 uv_run /home/ondrej/Projects/tsan/libuv/src/unix/core.c:385:5
	#19 nm_thread lib/isc/netmgr/netmgr.c:500:11

      Location is heap block of size 132 at 0x000000000030 allocated by thread T3:
	#0 malloc <null>
	#1 default_memalloc lib/isc/mem.c:713:8
	#2 mem_get lib/isc/mem.c:622:8
	#3 mem_allocateunlocked lib/isc/mem.c:1268:8
	#4 isc___mem_allocate lib/isc/mem.c:1288:7
	#5 isc__mem_allocate lib/isc/mem.c:2453:10
	#6 isc___mem_get lib/isc/mem.c:1037:11
	#7 isc__mem_get lib/isc/mem.c:2432:10
	#8 create_node lib/dns/rbt.c:2239:9
	#9 dns_rbt_addnode lib/dns/rbt.c:1435:12
	#10 findnodeintree lib/dns/rbtdb.c:2895:12
	#11 findnode lib/dns/rbtdb.c:2941:10
	#12 dns_db_findnode lib/dns/db.c:439:11
	#13 diff_apply lib/dns/diff.c:306:5
	#14 dns_diff_apply lib/dns/diff.c:459:10
	#15 do_one_tuple lib/ns/update.c:444:11
	#16 update_one_rr lib/ns/update.c:495:10
	#17 update_action lib/ns/update.c:3123:6
	#18 dispatch lib/isc/task.c:1152:7
	#19 run lib/isc/task.c:1344:2

      Mutex M1 is already destroyed.

      Mutex M2 is already destroyed.

      Mutex M3 is already destroyed.

      Thread T1 (running) created by main thread at:
	#0 pthread_create <null>
	#1 isc_thread_create lib/isc/pthreads/thread.c:73:8
	#2 isc_taskmgr_create lib/isc/task.c:1434:3
	#3 create_managers bin/named/main.c:915:11
	#4 setup bin/named/main.c:1223:11
	#5 main bin/named/main.c:1523:2

      Thread T2 (running) created by main thread at:
	#0 pthread_create <null>
	#1 isc_thread_create lib/isc/pthreads/thread.c:73:8
	#2 isc_nm_start lib/isc/netmgr/netmgr.c:223:3
	#3 create_managers bin/named/main.c:909:15
	#4 setup bin/named/main.c:1223:11
	#5 main bin/named/main.c:1523:2

      Thread T3 (running) created by main thread at:
	#0 pthread_create <null>
	#1 isc_thread_create lib/isc/pthreads/thread.c:73:8
	#2 isc_taskmgr_create lib/isc/task.c:1434:3
	#3 create_managers bin/named/main.c:915:11
	#4 setup bin/named/main.c:1223:11
	#5 main bin/named/main.c:1523:2

    SUMMARY: ThreadSanitizer: data race in memmove
74 jobs for !4149 with 2158-threadsanitizer-data-race-in-memmove in 19 minutes and 54 seconds (queued for 10 seconds)
detached
Status Job ID Name Coverage
  Autoconf
passed #1169592
linux amd64
autoreconf

00:00:18

 
  Precheck
passed #1169594
linux amd64
clang-format

00:00:17

passed #1169595
linux amd64
coccinelle

00:03:28

passed #1169596
linux amd64
danger

00:00:18

passed #1169593
linux amd64
misc

00:00:12

passed #1169597
linux amd64
tarball-create

00:01:27

 
  Build
passed #1169610
linux amd64
clang:asan

00:01:53

passed #1169614
linux amd64
clang:buster:amd64

00:00:57

passed #1169617
amd64 libvirt
clang:freebsd11:amd64

00:01:18

passed #1169618
amd64 libvirt
clang:freebsd12:amd64

00:01:09

passed #1169619
amd64 libvirt
clang:openbsd:amd64

00:02:44

passed #1169612
linux amd64
clang:tsan

00:01:10

passed #1169598
linux amd64
gcc:alpine3.12:amd64

00:00:54

passed #1169609
linux amd64
gcc:asan

00:01:35

passed #1169602
linux amd64
gcc:buster:amd64

00:00:47

passed #1169599
linux amd64
gcc:centos7:amd64

00:00:52

passed #1169600
linux amd64
gcc:centos8:amd64

00:00:51

passed #1169608
linux amd64
gcc:focal:amd64

00:00:48

passed #1169613
linux amd64
gcc:mutexatomics

00:00:50

passed #1169604
linux amd64
gcc:out-of-tree

00:00:52

passed #1169603
linux amd64
gcc:sid:amd64

00:01:07

passed #1169605
linux i386
gcc:sid:i386

00:01:13

passed #1169615
linux amd64
gcc:softhsm2.4

00:00:51

passed #1169616
linux amd64
gcc:softhsm2.6

00:00:52

passed #1169601
linux amd64
gcc:stretch:amd64

00:00:57

passed #1169611
linux amd64
gcc:tsan

00:00:59

passed #1169606
linux amd64
gcc:tumbleweed:amd64

00:00:48

passed #1169607
linux amd64
gcc:xenial:amd64

00:00:57

passed #1169620
amd64 windows
msvc:windows:amd64

00:00:44

 
  Unit
passed #1169632
linux amd64
unit:clang:asan

00:01:23

passed #1169636
linux amd64
unit:clang:buster:amd64

00:01:10

passed #1169639
amd64 libvirt
unit:clang:freebsd11:amd64

00:01:33

passed #1169640
amd64 libvirt
unit:clang:freebsd12:amd64

00:01:19

passed #1169634
linux amd64
unit:clang:tsan

00:03:00

passed #1169621
linux amd64
unit:gcc:alpine3.12:amd64

00:00:54

passed #1169631
linux amd64
unit:gcc:asan

00:01:24

passed #1169625
linux amd64
unit:gcc:buster:amd64

00:01:07

passed #1169622
linux amd64
unit:gcc:centos7:amd64

00:01:03

passed #1169623
linux amd64
unit:gcc:centos8:amd64

00:00:56

passed #1169630
linux amd64
unit:gcc:focal:amd64

00:01:08

passed #1169635
linux amd64
unit:gcc:mutexatomics

00:01:08

passed #1169626
linux amd64
unit:gcc:sid:amd64

00:01:11

passed #1169627
linux i386
unit:gcc:sid:i386

00:01:19

passed #1169637
linux amd64
unit:gcc:softhsm2.4

00:01:03

passed #1169638
linux amd64
unit:gcc:softhsm2.6

00:01:01

passed #1169624
linux amd64
unit:gcc:stretch:amd64

00:01:08

passed #1169633
linux amd64
unit:gcc:tsan

00:04:17

passed #1169628
linux amd64
unit:gcc:tumbleweed:amd64

00:01:14

passed #1169629
linux amd64
unit:gcc:xenial:amd64

00:01:11

 
  System
passed #1169652
linux amd64
system:clang:asan

00:13:07

passed #1169656
linux amd64
system:clang:buster:amd64

00:10:52

passed #1169659
amd64 libvirt
system:clang:freebsd11:amd64

00:10:05

passed #1169660
amd64 libvirt
system:clang:freebsd12:amd64

00:10:17

failed #1169654
linux amd64 allowed to fail
system:clang:tsan

00:14:05

passed #1169641
linux amd64
system:gcc:alpine3.12:amd64

00:12:06

passed #1169651
linux amd64
system:gcc:asan

00:12:58

passed #1169645
linux amd64
system:gcc:buster:amd64

00:11:07

passed #1169642
linux amd64
system:gcc:centos7:amd64

00:11:40

passed #1169643
linux amd64
system:gcc:centos8:amd64

00:11:50

passed #1169650
linux amd64
system:gcc:focal:amd64

00:11:37

passed #1169655
linux amd64
system:gcc:mutexatomics

00:11:02

passed #1169646
linux amd64
system:gcc:sid:amd64

00:11:45

passed #1169647
linux i386
system:gcc:sid:i386

00:12:39

passed #1169657
linux amd64
system:gcc:softhsm2.4

00:11:28

passed #1169658
linux amd64
system:gcc:softhsm2.6

00:11:08

passed #1169644
linux amd64
system:gcc:stretch:amd64

00:11:23

failed #1169653
linux amd64 allowed to fail
system:gcc:tsan

00:14:23

passed #1169648
linux amd64
system:gcc:tumbleweed:amd64

00:11:15

passed #1169649
linux amd64
system:gcc:xenial:amd64

00:10:48

 
  Docs
passed #1169661
linux amd64
docs

00:00:36

 
  Postcheck
passed #1169665
linux amd64
cppcheck

00:00:44

passed #1169662
linux amd64
flake8

00:00:19

passed #1169663
linux amd64
pylint

00:00:20

passed #1169664
linux amd64
scan-build

00:04:25

 
Name Stage Failure
failed
system:gcc:tsan System
No job log
failed
system:clang:tsan System
No job log