libbb: introduce kernel-style BUILD_BUG_ON()

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

networking/tc.c

@@ -64,15 +64,14 @@ struct globals {
 	uint32_t filter_proto;
 } FIX_ALIASING;
 #define G (*(struct globals*)&bb_common_bufsiz1)
-struct BUG_G_too_big {
-	char BUG_G_too_big[sizeof(G) <= COMMON_BUFSIZE ? 1 : -1];
-};
 #define filter_ifindex (G.filter_ifindex)
 #define filter_qdisc (G.filter_qdisc)
 #define filter_parent (G.filter_parent)
 #define filter_prio (G.filter_prio)
 #define filter_proto (G.filter_proto)
-#define INIT_G() do { } while (0)
+#define INIT_G() do { \
+	BUILD_BUG_ON(sizeof(G) > COMMON_BUFSIZE); \
+} while (0)
 
 /* Allocates a buffer containing the name of a class id.
  * The caller must free the returned memory.  */