GETDTABLECOUNT: adding new getdtablecount syscall from OpenBSD.
github-issue: #63
filedesc struct gets an additional counter for the number of file descriptors open in a per process basis.
Merge remote-tracking branch 'origin/hardened/current/master' into hardened/current/userlandenhanced
Merge branch 'hardened/current/master' into hardened/current/userlandenhanced

Conflicts:
	sys/compat/freebsd32/freebsd32_proto.h
	sys/compat/freebsd32/freebsd32_syscall.h
	sys/compat/freebsd32/freebsd32_syscalls.c
	sys/compat/freebsd32/freebsd32_sysent.c
	sys/compat/freebsd32/freebsd32_systrace_args.c
	sys/compat/freebsd32/syscalls.master
	sys/kern/init_sysent.c
	sys/kern/syscalls.c
	sys/kern/syscalls.master
	sys/kern/systrace_args.c
	sys/sys/syscall.h
	sys/sys/syscall.mk
	sys/sys/sysproto.h
GETDTABLECOUNT: changing approach to count file descriptors.
github-issue: #63
finally as advised by mjg@, finally withdraw the additional counter instead it counts the number of bits set in fd_map field. should not be roughly slower. does not use intentionally fdisused function to save at least a function call.
Merge remote-tracking branch 'origin/hardened/current/master' into hardened/current/userlandenhanced
Merge remote-tracking branch 'origin/hardened/current/master' into hardened/current/userlandenhanced
Correct a typo to fix chown(2).  It was broken since r274476.

Pointy hat to:	kib
X-MFC-With:	r274476
GETDTABLECOUNT: going until lastfile, less costly.
github-issue: #63
Migrate the callouts from using mutex locks to being mpsafe with
the locks being held by the callers.

Kill callout_drain() and use callout_stop().
Merge remote-tracking branch 'freebsd/master' into hardened/current/master
Merge remote-tracking branch 'origin/hardened/current/master' into hardened/current/userlandenhanced
Merge branch 'hardened/current/userlandenhanced' into hardened/current/unstable

Conflicts:
	lib/libc/sys/Symbol.map
	sys/compat/freebsd32/freebsd32_proto.h
	sys/compat/freebsd32/freebsd32_syscall.h
	sys/compat/freebsd32/freebsd32_syscalls.c
	sys/compat/freebsd32/freebsd32_sysent.c
	sys/compat/freebsd32/freebsd32_systrace_args.c
	sys/compat/freebsd32/syscalls.master
	sys/kern/init_sysent.c
	sys/kern/syscalls.c
	sys/kern/syscalls.master
	sys/kern/systrace_args.c
	sys/sys/syscall.h
	sys/sys/syscall.mk
	sys/sys/sysproto.h