SCUMM: Handle double-clicks in Mac Loom (bug #3588164)

Unlike the EGA DOS version, it doesn't seem to be the scripts
that keep track of double-clicks. Instead, the engine sets a
variable to indicate them. Unlike the DOS version, we don't check
that the second click happens close enough on the screen to the
first one. We could, but it seemed needlessly complicated.

NEWS

@@ -37,6 +37,7 @@ For a more comprehensive changelog of the latest experimental code, see:
      now uses the original instruments, rather than approximating them with
      General MIDI instruments, and should sound a lot closer to the original.
    - Added sound and music support for the Macintosh version of Loom.
+   - Handle double-clicking in the Macintosh version of Loom.
 
 1.5.0 (2012-07-27)
  New Games:

engines/scumm/script.cpp

@@ -1366,9 +1366,15 @@ void ScummEngine::runInputScript(int clickArea, int val, int mode) {
 
 		// Clicks are handled differently in Indy3 mac: param 2 of the
 		// input script is set to 0 for normal clicks, and to 1 for double clicks.
+		// The EGA DOS version of Loom also checks that the second click happens
+		// close enough to the first one, but that seems like overkill.
 		uint32 time = _system->getMillis();
 		args[2] = (time < _lastInputScriptTime + 500);	// 500 ms double click delay
 		_lastInputScriptTime = time;
+	} else if (_game.id == GID_LOOM && _game.platform == Common::kPlatformMacintosh) {
+		uint32 time = _system->getMillis();
+		VAR(52) = (time < _lastInputScriptTime + 500);	// 500 ms double click delay
+		_lastInputScriptTime = time;
 	}
 
 	if (verbScript)