apparmor: avoid -Wempty-body warning

Building with 'make W=1' shows a warning for an empty macro:

security/apparmor/label.c: In function '__label_update':
security/apparmor/label.c:2096:59: error: suggest braces around empty body in an 'else' statement [-Werror=empty-body]
 2096 |                 AA_BUG(labels_ns(label) != labels_ns(new));

Change the macro definition to use no_printk(), which improves
format string checking and avoids the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: John Johansen <john.johansen@canonical.com>

security/apparmor/include/lib.h

@@ -36,7 +36,7 @@
 #define AA_BUG_FMT(X, fmt, args...)					\
 	WARN((X), "AppArmor WARN %s: (" #X "): " fmt, __func__, ##args)
 #else
-#define AA_BUG_FMT(X, fmt, args...)
+#define AA_BUG_FMT(X, fmt, args...) no_printk(fmt, ##args)
 #endif
 
 #define AA_ERROR(fmt, args...)						\