[PATCH] kconfig: clarify memory debug options

The Kconfig text for CONFIG_DEBUG_SLAB and CONFIG_DEBUG_PAGEALLOC have always
seemed a bit confusing.  Change them to:

CONFIG_DEBUG_SLAB: "Debug slab memory allocations"
CONFIG_DEBUG_PAGEALLOC: "Debug page memory allocations"

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>