control socket poll() (select()), fstat(), and accept() operations,
required for some policies:
poll() mac_check_socket_poll()
fstat() mac_check_socket_stat()
accept() mac_check_socket_accept()
Update mac_stub and mac_test policies to be aware of these entry points.
While here, add missing entry point implementations for:
mac_stub.c stub_check_socket_receive()
mac_stub.c stub_check_socket_send()
mac_test.c mac_test_check_socket_send()
mac_test.c mac_test_check_socket_visible()
Obtained from: TrustedBSD Project
Sponsored by: SPAWAR, SPARTA