Fix compiling on OS X
Update to latest SDLMain from SDL-1.2

This also fixes the 10.9+ entry point bug where loading would
immediately exit http://hg.libsdl.org/SDL/rev/cfec3f86fba7
Merge pull request #17 from clobber/osx-buildfix

Fix compiling on OS X
Merge pull request #18 from clobber/osx-sdlmain-fix

Fix 10.9+ and update to latest SDLMain from SDL-1.2