AU: gitignore update

This ignores temporary directories used for unit testing; apparently,
devs tend to run unit tests inside their source directory, e.g. using
./run_unittests, so this is annoying.

BUG=None
TEST=Directories ignored by git

Change-Id: I4ad67909605d899c78e8579b3981f39d8c8dd2fe
Reviewed-on: https://gerrit.chromium.org/gerrit/56298
Reviewed-by: Chris Sosa <sosa@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
diff --git a/.gitignore b/.gitignore
index e22ca50..9b20783 100644
--- a/.gitignore
+++ b/.gitignore
@@ -27,3 +27,6 @@
 /update_engine_unittests
 /update_metadata.pb.cc
 /update_metadata.pb.h
+/UpdateAttempterTest/
+/omaha_request_action-test/
+/omaha_response_handler_action-test/