Use int instead of size_t to silence warning

gcc-4.4.1 was complaining:

fontconv.c: In function ‘mapWeightToName’:
fontconv.c:114: warning: field precision should have type ‘int’, but argument 4 has type ‘size_t’
fontconv.c:114: warning: field precision should have type ‘int’, but argument 4 has type ‘size_t’
fontconv.c: In function ‘xlfdToFc’:
fontconv.c:157: warning: field precision should have type ‘int’, but argument 4 has type ‘size_t’
fontconv.c:157: warning: field precision should have type ‘int’, but argument 4 has type ‘size_t’

util/fontconv.c

@@ -45,7 +45,7 @@ static int countChar(char *str, char c)
 
 typedef struct str {
 	char *str;
-	size_t len;
+	int len;
 } str;
 
 #define XLFD_TOKENS 14