[nacltoons] Remove legacy nacl_mounts support.

Roll cocos2dx to a version that also has nacl_mounts
removed.

R=binji

Review URL: https://codereview.chromium.org/12472014

git-svn-id: https://nativeclient-sdk.googlecode.com/svn/trunk/src@1520 050acbb0-2703-11df-ab0a-9f3f633ae91d