Disable building simulator for "x86_64"

The buildbot have an old SDK / Xcode installed that does not
support building a simulator target for "x86_64".

BUG=chromium:322075
R=thakis@chromium.org
CC=justincohen@chromium.org

Review URL: https://codereview.chromium.org/88813002

git-svn-id: http://gyp.googlecode.com/svn/trunk@1799 78cadc50-ecff-11dd-a971-7dbc132099af
2 files changed