This lets SDL-based apps respond to "Open With" commands properly, as they
can now obtain the requested path via a standard SDL dropfile event.
This is only checked on startup, so apps don't get drop events at any other
time, even if Android supports that, but this is still a definite
improvement.
Fixes Bugzilla #2762.
An existing hint lets apps that don't need the timer resolution changed avoid
this, to save battery, etc, but this fixes several problems in timing, audio
callbacks not firing fast enough, etc.
Fixes Bugzilla #2944.
