Patch for held double-click startup bug on Windows

It would be nice if someone could review the patch and test it since it’s a rather important issue that should be dealth with quickly.

The bug: https://bugzilla.libsdl.org/show_bug.cgi?id=2520

The patch: https://www.dropbox.com/s/r0zo7aqwvtgzz93/SDL_2520.patch

Additional notes:

  • the patch has gone through basic testing - it doesn’t break anything as far as casual usage goes, it restores the initial mouse motion event and re-enables first click events on held double-click app startup
  • the issue was directly caused by WIN_CheckAsyncMouseRelease, in that it detected a click that did not occur on initial window activation, which is why it may only release outdated button presses with the patch

P.S. Is there some simple way to run the test suite? I built it with VS but there seem to be bugs, preventing me from running it.------------------------
SGScript scripting engine (http://www.sgscript.org)