It's the subdir where the implementation also lives. There's no
src/widgets/gestures, either.
Change the mac: into a darwin: scope in the .pro file, so Sanity Bot
does not complain.
Change-Id: I7608d6da05af4a1117db585798a87a20ae80717a
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
