[PATCH] pid: export the symbols needed to use struct pid *

pids aren't something that drivers should care about.  However there are a lot
of helper layers in the kernel that do care, and are built as modules.  Before
I can convert them to using struct pid instead of pid_t I need to export the
appropriate symbols so they can continue to be built.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>