PC-BSD/trueos cb192b5lib/libc/sys fhlink.2 getfh.2, sys/compat/freebsd32 freebsd32_systrace_args.c syscalls.master

MFC r341689, r341711, r341712, r341809:
Add getfhat(2), fhlink(2), fhlinkat(2), fhreadlink(2) file handle system calls.

To easier potential MFC of the AT_BENEATH feature, some vestiges of it were
left in the merged product but commented out.

Due to a lot of conflicts, it was impossible to split the merge and
regeneration of the syscall tables, because I needed to test the result.
It is fine for stable branch to commit the whole change with the
generated diff.
DeltaFile
+268-0lib/libc/sys/fhlink.2
+195-60sys/kern/vfs_syscalls.c
+124-2lib/libc/sys/getfh.2
+120-0sys/kern/systrace_args.c
+120-0sys/compat/freebsd32/freebsd32_systrace_args.c
+92-0lib/libc/sys/fhreadlink.2
+28-0sys/sys/sysproto.h
+28-0sys/kern/syscalls.master
+7-0sys/compat/freebsd32/syscalls.master
+7-0lib/libc/sys/Symbol.map
+5-1sys/sys/syscall.h
+5-1sys/sys/syscall.mk
+5-1sys/compat/freebsd32/freebsd32_syscall.h
+4-1lib/libc/sys/Makefile.inc
+4-0sys/sys/mount.h
+4-0sys/compat/freebsd32/freebsd32_syscalls.c
+4-0sys/kern/syscalls.c
+4-0sys/compat/freebsd32/freebsd32_sysent.c
+4-0sys/kern/init_sysent.c
+1,028-6619 files

UnifiedSplitRaw