t/perf: add "trash directory" to .gitignore

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/perf/.gitignore b/t/perf/.gitignore
index 50f5cc1..982eb8e 100644
--- a/t/perf/.gitignore
+++ b/t/perf/.gitignore
@@ -1,2 +1,3 @@
-build/
-test-results/
+/build/
+/test-results/
+/trash directory*/