Android: Use native platform menus.

This is an Android only patch, a proper implementation
will be pushed soon to stable branch.


Task-number: QTBUG-29462
Task-number: QTBUG-33588

Change-Id: I3447c523b4533a768d7f95e4ae60541b09a7944f
Reviewed-by: Christoph Schleifenbaum <christoph.schleifenbaum@kdab.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>
tst_QWindow: Set explicit window position to please qWaitForWindowActive

qWaitForWindowActive waits until the timeout for the window to receive
a non-0x0 position, even when it's active, just in case the WM sets
the position as a response to focus-in.

Change-Id: I748cce2747f406a8cdff556465175f02675fcd13
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>
iOS: Don't enable kEAGLDrawablePropertyRetainedBacking

We report our swap-behavior as QSurfaceFormat::DoubleBuffer, which means
there's no point in using retained backing. This was a left-over from
when we reported single-buffered swaps, which didn't work to well as
clients would wrongly assume swap was not needed at all.

Change-Id: Id26df2f8b282892c720d48cfe85eb9e010f1500d
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>