- fix a potential file descriptor leak in server side of pak downloading

- add new functions for banning clients from server, in engine part. This will also make it possible to ban ipv6 addresses in old mods.

code/qcommon/files.c

@@ -715,7 +715,8 @@ int FS_SV_FOpenFileRead( const char *filename, fileHandle_t *fp ) {
 	if (f) {
 		return FS_filelength(f);
 	}
-	return 0;
+
+	return -1;
 }