Roland added this include with his 'waitid system call' patch, which was
removed again after a while.  Just the header inclusion was not removed.

http://linux.bkbits.net:8080/linux-2.5/cset@4134b6dd1rY3qnaq7YABrXPXGvzzpw
http://linux.bkbits.net:8080/linux-2.5/cset@41499f66EDHON_8B1FYGEzLZQ2u13QSigned-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>