Remove warnings and make wc WARNS=6 clean.

Add FreeBSD Id to Makefile.

Approved by:	ssouhlal

usr.bin/wc/Makefile

@@ -1,5 +1,6 @@
 #	@(#)Makefile	8.1 (Berkeley) 6/6/93
+# $FreeBSD$
 
 PROG=	wc
-
+WARNS?=	6
 .include <bsd.prog.mk>

usr.bin/wc/wc.c

@@ -69,9 +69,7 @@ static int	cnt(const char *);
 static void	usage(void);
 
 int
-main(argc, argv)
-	int argc;
-	char *argv[];
+main(int argc, char *argv[])
 {
 	int ch, errors, total;
 
@@ -133,8 +131,7 @@ main(argc, argv)
 }
 
 static int
-cnt(file)
-	const char *file;
+cnt(const char *file)
 {
 	struct stat sb;
 	uintmax_t linect, wordct, charct;