There's no help text for CONFIG_DEBUG_STACKOVERFLOW - add one.

Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>