Fixes an exception on goma cleanup.
Fixes an exception on goma cleanup.

This fixes an issue where the 'output_file' variable is used before it's
rdefined when the Goma function fails.

BUG=None
TEST=None

Review URL: https://codereview.chromium.org/1011163003

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@294478 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build