remove trailing whitespace

lib/roken/concat.c

@@ -78,7 +78,7 @@ roken_vmconcat (char **s, size_t max_len, va_list args)
     len = 1;
     while ((a = va_arg(args, const char*))) {
 	size_t n = strlen (a);
-	
+
 	if(max_len && len + n > max_len){
 	    free(p);
 	    return 0;