scan-tree.c: avoid memory leak

No references are kept to the memory pointed to by the 'rel' variable, so
it should be free()'d before returning from add_repo().

Signed-off-by: Jamie Couture <jamie.couture@gmail.com>
Signed-off-by: Lars Hjemli <larsh@hjemli.net>

scan-tree.c

@@ -155,6 +155,8 @@ static void add_repo(const char *base, const char *path, repo_config_fn fn)
 		config_fn = fn;
 		parse_configfile(xstrdup(p), &repo_config);
 	}
+
+	free(rel);
 }
 
 static void scan_path(const char *base, const char *path, repo_config_fn fn)