Lift MEDIA_MMX_INTRINSICS_AVAILABLE definition to header and use it to condition media_unittests


BUG=173697, 166496
TEST=With other build errors fixed in privates (fix win64 gmock_mutant template functor redefinitions & ignore C4267 size_t to int truncations), win64 media_unittests builds without link error to (shared library) media::FilterYUVRows_MMX
R=scherkus@chromium.org


Review URL: https://chromiumcodereview.appspot.com/12213029

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@181344 0039d316-1c4b-4281-b951-d872f2087c98
3 files changed