Build failure on FreeBSD

Commit 8ddc54e2 failed to build on FreeBSD 11.1.

libtool: compile:  gcc -include /usr/home/jenkins/workspace/bind9-master-freebsd11-64/config.h -I/usr/home/jenkins/workspace/bind9-master-freebsd11-64 -I../.. -I./unix/include -I./pthreads/include -I./include -I./include -I/usr/home/jenkins/workspace/bind9-master-freebsd11-64/lib/dns/include -I../../lib/dns/include -I/usr/local/include -DISC_MEM_DEFAULTFILL=1 -DISC_LIST_CHECKINIT=1 -g -O2 -pthread -I /usr/local/include -I/usr/local/include/libxml2 -I/usr/include -fPIC -W -Wall -Wmissing-prototypes -Wcast-qual -Wwrite-strings -Wformat -Wpointer-arith -fno-strict-aliasing -fno-delete-null-pointer-checks -Wshadow -Werror -c siphash.c  -fPIC -DPIC -o .libs/siphash.o
In file included from siphash.c:36:0:
./include/isc/endian.h:46:0: error: "be16toh" redefined [-Werror]
 # define be16toh(x) betoh16(x)
 
In file included from ./include/isc/endian.h:44:0,
                 from siphash.c:36:
/usr/include/sys/endian.h:75:0: note: this is the location of the previous definition
 #define be16toh(x) bswap16((x))
 
In file included from siphash.c:36:0:
./include/isc/endian.h:47:0: error: "le16toh" redefined [-Werror]
 # define le16toh(x) letoh16(x)
 
In file included from ./include/isc/endian.h:44:0,
                 from siphash.c:36:
/usr/include/sys/endian.h:78:0: note: this is the location of the previous definition
 #define le16toh(x) ((uint16_t)(x))
 
In file included from siphash.c:36:0:
./include/isc/endian.h:49:0: error: "be32toh" redefined [-Werror]
 # define be32toh(x) betoh32(x)
 
In file included from ./include/isc/endian.h:44:0,
                 from siphash.c:36:
/usr/include/sys/endian.h:76:0: note: this is the location of the previous definition
 #define be32toh(x) bswap32((x))
 
In file included from siphash.c:36:0:
./include/isc/endian.h:50:0: error: "le32toh" redefined [-Werror]
 # define le32toh(x) letoh32(x)
 
In file included from ./include/isc/endian.h:44:0,
                 from siphash.c:36:
/usr/include/sys/endian.h:79:0: note: this is the location of the previous definition
 #define le32toh(x) ((uint32_t)(x))
 
In file included from siphash.c:36:0:
./include/isc/endian.h:52:0: error: "be64toh" redefined [-Werror]
 # define be64toh(x) betoh64(x)
 
In file included from ./include/isc/endian.h:44:0,
                 from siphash.c:36:
/usr/include/sys/endian.h:77:0: note: this is the location of the previous definition
 #define be64toh(x) bswap64((x))
 
In file included from siphash.c:36:0:
./include/isc/endian.h:53:0: error: "le64toh" redefined [-Werror]
 # define le64toh(x) letoh64(x)
 
In file included from ./include/isc/endian.h:44:0,
                 from siphash.c:36:
/usr/include/sys/endian.h:80:0: note: this is the location of the previous definition
 #define le64toh(x) ((uint64_t)(x))
 
In file included from siphash.c:36:0:
siphash.c: In function 'isc_siphash24':
./include/isc/endian.h:53:21: error: implicit declaration of function 'letoh64' [-Werror=implicit-function-declaration]
 # define le64toh(x) letoh64(x)
                     ^
siphash.c:62:16: note: in expansion of macro 'le64toh'
  uint64_t k0 = le64toh(key[0]);
                ^~~~~~~
cc1: all warnings being treated as errors
*** Error code 1

Stop.
make[2]: stopped in /usr/home/jenkins/workspace/bind9-master-freebsd11-64/lib/isc
*** Error code 1

Stop.
make[1]: stopped in /usr/home/jenkins/workspace/bind9-master-freebsd11-64/lib
*** Error code 1

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