access to POSIX Semaphores:

mac_init_posix_sem()            Initialize label for POSIX semaphore
mac_create_posix_sem()          Create POSIX semaphore
mac_destroy_posix_sem()         Destroy POSIX semaphore
mac_check_posix_sem_destroy()   Check whether semaphore may be destroyed
mac_check_posix_sem_getvalue()  Check whether semaphore may be queried
mac_check_possix_sem_open()     Check whether semaphore may be opened
mac_check_posix_sem_post()      Check whether semaphore may be posted to
mac_check_posix_sem_unlink()    Check whether semaphore may be unlinked
mac_check_posix_sem_wait()      Check whether may wait on semaphore

Update Biba, MLS, Stub, and Test policies to implement these entry points.
For information flow policies, most semaphore operations are effectively
read/write.

Submitted by:	Dandekar Hrishikesh <rishi_dandekar at sbcglobal dot net>
Sponsored by:	DARPA, McAfee, SPARTA
Obtained from:	TrustedBSD Project

Option 'P1003_1B_SEMAPHORES' to compile them in, or load the "sem" module
to activate them.

Have kern/makesyscalls.sh emit an include for sys/_semaphore.h into sysproto.h
to pull in the typedef for semid_t.

Add the syscalls to the syscall table as module stubs.