capability.h warning fix

include/linux/capability.h:397: warning: "struct task_struct" declared inside parameter list
include/linux/capability.h:397: warning: its scope is only this definition or declaration, which is probably not what you want

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>