[PATCH] Prevent multiple inclusion of linux/sysrq.h

Prevent multiple inclusions of include/linux/sysrq.h using traditional
#ifndef..#endif.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@enix.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>