[nacltoons] Add level selection screen.

Also, remove -lnosys to fix linker warnings.

BUG=None

Review URL: https://codereview.chromium.org/12634007

git-svn-id: https://nativeclient-sdk.googlecode.com/svn/trunk/src@1524 050acbb0-2703-11df-ab0a-9f3f633ae91d
13 files changed