In non-debugging mode make this define (void)0 instead of nothing. This

helps to catch bugs like the below with clang.

	if (cond);		<--- note the trailing ;
	   something();

Approved by:	ed (mentor)
Discussed on:	current@

sys/net/bridgestp.c

@@ -68,7 +68,7 @@ __FBSDID("$FreeBSD$");
 #ifdef	BRIDGESTP_DEBUG
 #define	DPRINTF(fmt, arg...)	printf("bstp: " fmt, ##arg)
 #else
-#define	DPRINTF(fmt, arg...)
+#define	DPRINTF(fmt, arg...)	(void)0
 #endif
 
 #define	PV2ADDR(pv, eaddr)	do {		\