Unify /proc/slabinfo configuration

Both SLUB and SLAB really did almost exactly the same thing for
/proc/slabinfo setup, using duplicate code and per-allocator #ifdef's.

This just creates a common CONFIG_SLABINFO that is enabled by both SLUB
and SLAB, and shares all the setup code.  Maybe SLOB will want this some
day too.

Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/init/Kconfig b/init/Kconfig
index 404bbf3..b9d11a8 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -658,6 +658,12 @@
 
 endmenu		# General setup
 
+config SLABINFO
+	bool
+	depends on PROC_FS
+	depends on SLAB || SLUB
+	default y
+
 config RT_MUTEXES
 	boolean
 	select PLIST