Ignore output files from indent tests.
diff --git a/.gitignore b/.gitignore
index f31e233..5691e22 100644
--- a/.gitignore
+++ b/.gitignore
@@ -80,6 +80,7 @@
 src/testdir/messages
 src/testdir/viminfo
 src/testdir/opt_test.vim
+runtime/indent/testdir/*.out
 src/memfile_test
 src/json_test
 src/message_test