Add fallback function for endian(3) family functions in isc/endian.h

Write simple bswap{16,32,64} macros and use them in place where
byteorder(3) functions are not appropriate (e.g. bigendian platforms
and 64-bit functions).
41 jobs for !1973 with 605-make-endian.h-more-portable in 20 minutes and 11 seconds (queued for 3 seconds)
detached
Status Job ID Name Coverage
  Precheck
passed #237737
linux amd64
🐞:sid:amd64

00:00:13

passed #237736
linux amd64
misc:sid:amd64

00:00:17

 
  Build
passed #237748
linux amd64
asan:sid:amd64

00:01:50

passed #237749
linux amd64
clang:stretch:amd64

00:01:14

passed #237750
linux i386
clang:stretch:i386

00:01:49

passed #237738
linux amd64
docs:sid:amd64

00:00:44

passed #237747
linux amd64
gcc:bionic:amd64

00:01:41

passed #237739
linux amd64
gcc:centos6:amd64

00:02:54

passed #237740
linux amd64
gcc:centos7:amd64

00:01:56

passed #237745
linux amd64
gcc:fedora29:amd64

00:02:29

passed #237741
linux amd64
gcc:jessie:amd64

00:01:28

passed #237743
linux amd64
gcc:sid:amd64

00:01:14

passed #237744
linux i386
gcc:sid:i386

00:01:16

passed #237742
linux amd64
gcc:stretch:amd64

00:01:06

passed #237746
linux amd64
gcc:xenial:amd64

00:01:19

passed #237751
linux amd64
pkcs11:sid:amd64

00:01:43

 
  Test
passed #237770
linux amd64
system:asan:sid:amd64

00:09:24

passed #237768
linux amd64
system:gcc:bionic:amd64

00:07:45

passed #237944
linux amd64
system:gcc:centos6:amd64

00:07:24

passed #237754
linux amd64
system:gcc:centos7:amd64

00:07:54

passed #237764
linux amd64
system:gcc:fedora29:amd64

00:08:01

passed #237756
linux amd64
system:gcc:jessie:amd64

00:08:03

passed #237760
linux amd64
system:gcc:sid:amd64

00:07:01

passed #237762
linux i386
system:gcc:sid:i386

00:07:01

passed #237758
linux amd64
system:gcc:stretch:amd64

00:08:02

passed #237766
linux amd64
system:gcc:xenial:amd64

00:07:37

passed #237942
linux amd64
system:pkcs11:sid:amd64

00:07:54

passed #237771
linux amd64
unit:asan:sid:amd64

00:01:12

passed #237772
linux amd64
unit:clang:stretch:amd64

00:00:44

passed #237769
linux amd64
unit:gcc:bionic:amd64

00:00:44

passed #237753
linux amd64
unit:gcc:centos6:amd64

00:00:48

passed #237755
linux amd64
unit:gcc:centos7:amd64

00:00:50

passed #237765
linux amd64
unit:gcc:fedora29:amd64

00:00:48

passed #237757
linux amd64
unit:gcc:jessie:amd64

00:00:41

passed #237761
linux amd64
unit:gcc:sid:amd64

00:01:00

passed #237763
linux i386
unit:gcc:sid:i386

00:00:46

passed #237759
linux amd64
unit:gcc:stretch:amd64

00:00:45

passed #237767
linux amd64
unit:gcc:xenial:amd64

00:00:49

passed #237774
linux amd64
unit:pkcs11:sid:amd64

00:00:55

failed #237752
linux amd64
system:gcc:centos6:amd64

00:09:21

failed #237773
linux amd64
system:pkcs11:sid:amd64

00:08:07