Mac bug fix for 1.7.4: onWindowFocusChange()

I reported to GG a while ago that the onWindowFocusChange() callback does not get called on the Mac build, but does on Windows.

Since they've not fixed this yet, I found the fix myself. Open macCarbEvents.cc and find the _onActivate() method. Modify it like so:

//-----------------------------------------------------------------------------
static void _OnActivate(bool activating)
{
   if(activating)
   {
      Input::activate();
      Game->refreshWindow();
      platState.backgrounded = false;
      pthread_kill((pthread_t)platState.torqueThreadId, SIGALRM);
      
      Con::executef(2, "onWindowFocusChange", "1");
   }
   else
   {
      Input::deactivate();
      platState.backgrounded = true;
      
      Con::executef(2, "onWindowFocusChange", "0");
   }
}

All I added was the two "Con::execute" lines -- don't change anything else.

Just posting this in case anyone else finds it helpful.

Still frustrated that really easy-to-fix, basic bugs like this have gone unfixed for months/years, despite being reported. Sigh.