Merge pull request #1 from stepmania/master

Update
Preserves backwards compatibility with 10.6

sync_volume_np was introduced in the 10.8 SDK. This commit ensures that
some related constants are defined before calling the function. If they
are not, we fallback to the older logic.
Merge pull request #358 from jberney/master

Band-aid fix for Mac OS X fullscreen issues (only when compiled with 10.6 SDK)