taint: add explicit flag to show whether lock dep is still OK.

Fix up all callers as they were before, with make one change: an
unsigned module taints the kernel, but doesn't turn off lockdep.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/mm/slub.c b/mm/slub.c
index ba2ca53..7ec3041b 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -562,7 +562,7 @@
 	printk(KERN_ERR "----------------------------------------"
 			"-------------------------------------\n\n");
 
-	add_taint(TAINT_BAD_PAGE);
+	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 }
 
 static void slab_fix(struct kmem_cache *s, char *fmt, ...)