chromeos: Update .gitignore for build-related files.

This makes us ignore out_* (per-board output directories,
e.g. out_x86-generic) and c (a symlink created by the Chrome
OS ebuild to limit the length of some command lines).

BUG=chromium-os:7967
TEST=ran "git status"

Review URL: http://codereview.chromium.org/5535005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@68366 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed