I believe a recent commit broke something:
cc -DHAVE_CONFIG_H -DCOMPILE_ONLY -I/usr/src/lib/libmagic -I/usr/src/lib/libmagic/../../contrib/file-4.12/src -o mkmagic /usr/src/lib/libmagic/../../contrib/file-4.12/src/apprentice.c /usr/src/lib/libmagic/../../contrib/file-4.12/src/funcs.c /usr/src/lib/libmagic/../../contrib/file-4.12/src/magic.c /usr/src/lib/libmagic/../../contrib/file-4.12/src/print.c
/usr/obj/usr/src/world_i386/usr/lib/libc.so: undefined reference to `__ftrylockfile_stub'
*** Error code 1
Stop in /usr/src/lib/libmagic.
*** Error code 1
Peter