Make goma canary run goma with GOMA_HERMETIC=error.
Make goma canary run goma with GOMA_HERMETIC=error.

Before turning on GOMA_HERMETIC=error on anything else, let me set
GOMA_HERMETIC=error on goma's trybot to see the effect of the flag.
BUG=https://code.google.com/p/chromium/issues/detail?id=366967

Review URL: https://codereview.chromium.org/878033002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@293835 0039d316-1c4b-4281-b951-d872f2087c98

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