kasan: only select SLUB_DEBUG with SYSFS=y

Building with KASAN and SLUB but without sysfs now results in a
build-time error:

  WARNING: unmet direct dependencies detected for SLUB_DEBUG
    Depends on [n]: SLUB [=y] && SYSFS [=n]
    Selected by [y]:
    - KASAN [=y] && HAVE_ARCH_KASAN [=y] && (SLUB [=y] || SLAB [=n] && !DEBUG_SLAB [=n]) && SLUB [=y]
  mm/slub.c:4565:12: error: 'list_locations' defined but not used [-Werror=unused-function]
   static int list_locations(struct kmem_cache *s, char *buf,
              ^~~~~~~~~~~~~~
  mm/slub.c:4406:13: error: 'validate_slab_cache' defined but not used [-Werror=unused-function]
   static long validate_slab_cache(struct kmem_cache *s)

This disallows that broken configuration in Kconfig.

Link: http://lkml.kernel.org/r/[email protected]
Fixes: dd275ca ("kasan: depend on CONFIG_SLUB_DEBUG")
Signed-off-by: Arnd Bergmann <[email protected]>
Cc: "Jason A. Donenfeld" <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Christoph Lameter <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

lib/Kconfig.kasan

@@ -5,7 +5,7 @@ if HAVE_ARCH_KASAN
 
 config KASAN
 	bool "KASan: runtime memory debugger"
-	depends on SLUB || (SLAB && !DEBUG_SLAB)
+	depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB)
 	select SLUB_DEBUG if SLUB
 	select CONSTRUCTORS
 	select STACKDEPOT