Add cgit_query.nohead flag

This flag is set when no HEAD is specified in the querystring. Currently
it has no users, but it will be used by ui-snapshot to invoke a DWIM-mode
where the revision is extracted from the snapshot name.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

cgit.h

@@ -120,6 +120,7 @@ struct cgit_query {
 	char *mimetype;
 	char *url;
 	int   ofs;
+	int nohead;
 };
 
 struct cgit_config {