Check in a ninja binary for Linux x64 and Mac.

The shell script currently just assumes Linux, but can be
fixed to run the Mac binary when appropriate.

Review URL: http://codereview.chromium.org/9212017

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@117723 0039d316-1c4b-4281-b951-d872f2087c98

ninja

+#!/bin/sh
+
+exec ninja-linux64 "$@"