android: Set gcc_version in build/common.gypi instead of in envsetup.

BUG=330631
R=torne@chromium.org

Review URL: https://codereview.chromium.org/136073002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244615 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244615