Missing locks when accessing keynode.initial and keynode.managed triggered TSAN.

Job #1190729 failed for 96d2ec16:

WARNING: ThreadSanitizer: data race 
  Write of size 1 at 0x000000000001 by thread T1 (mutexes: write M1):
    #0 dns_keynode_trust lib/dns/keytable.c:836
    #1 keyfetch_done lib/dns/zone.c:10187
    #2 dispatch lib/isc/task.c:1152
    #3 run lib/isc/task.c:1344
    #4 <null> <null>

  Previous read of size 1 at 0x000000000001 by thread T2 (mutexes: read M2):
    #0 keynode_dslist_totext lib/dns/keytable.c:682
    #1 dns_keytable_totext lib/dns/keytable.c:732
    #2 named_server_dumpsecroots bin/named/server.c:11357
    #3 named_control_docommand bin/named/control.c:264
    #4 control_command bin/named/controlconf.c:390
    #5 dispatch lib/isc/task.c:1152
    #6 run lib/isc/task.c:1344
    #7 <null> <null>

  Location is heap block of size 241 at 0x000000000010 allocated by thread T3:
    #0 malloc <null>
    #1 default_memalloc lib/isc/mem.c:713
    #2 mem_get lib/isc/mem.c:622
    #3 mem_allocateunlocked lib/isc/mem.c:1268
    #4 isc___mem_allocate lib/isc/mem.c:1288
    #5 isc__mem_allocate lib/isc/mem.c:2453
    #6 isc___mem_get lib/isc/mem.c:1037
    #7 isc__mem_get lib/isc/mem.c:2432
    #8 new_keynode lib/dns/keytable.c:346
    #9 insert lib/dns/keytable.c:393
    #10 dns_keytable_add lib/dns/keytable.c:421
    #11 process_key bin/named/server.c:955
    #12 load_view_keys bin/named/server.c:983
    #13 configure_view_dnsseckeys bin/named/server.c:1140
    #14 configure_view bin/named/server.c:5371
    #15 load_configuration bin/named/server.c:9110
    #16 loadconfig bin/named/server.c:10310
    #17 named_server_reconfigcommand bin/named/server.c:10693
    #18 named_control_docommand bin/named/control.c:250
    #19 control_command bin/named/controlconf.c:390
    #20 dispatch lib/isc/task.c:1152
    #21 run lib/isc/task.c:1344
    #22 <null> <null>

  Mutex M1 is already destroyed.

  Mutex M2 is already destroyed.

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

  Thread T2 (running) created by main thread at:
    #0 pthread_create <null>
    #1 isc_thread_create pthreads/thread.c:73
    #2 isc_taskmgr_create lib/isc/task.c:1434
    #3 create_managers bin/named/main.c:915
    #4 setup bin/named/main.c:1223
    #5 main bin/named/main.c:1523

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

SUMMARY: ThreadSanitizer: data race lib/dns/keytable.c:836 in dns_keynode_trust