ui-plain: fix resource leak: free before return

Coverity-id: 13940
Signed-off-by: Christian Hesse <mail@eworm.de>
diff --git a/ui-plain.c b/ui-plain.c
index 0dd1a8b..4c73607 100644
--- a/ui-plain.c
+++ b/ui-plain.c
@@ -51,6 +51,7 @@
 	cgit_print_http_headers();
 	html_raw(buf, size);
 	free(mimetype);
+	free(buf);
 	return 1;
 }