osxvideo: fix mac os 10.14 build; fixes #577
lockFocusIfCanDraw is deprecated in mac os 10.14. Apple suggests a different way to do what that does, but for now, just suppress the deprecation.
There's no way to disable just that deprecation, so shut them all down.
OpenGL is also deprecated in mac os 10.14. There is a gentle way to turn off just those deprecations (GL_SILENCE_DEPRECATION), but since this commit turns them all off, that's moot.