New helper: current_thread_info().  Allows to do a bunch of odd syscalls
in C. While we are at it, there had never been a reason to do
osf_getpriority() in assembler.  We also get "namespace"-aware (read:
consistent with getuid(2), etc.) behaviour from getx?id() syscalls now.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NMichael Cree <mcree@orcon.net.nz>
Acked-by: NMatt Turner <mattst88@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>