Android: Make platform menu more robust

Don't crash and lock up the whole device when people try to
remove menu items that don't exist.

Task-number: QTBUG-34246
Change-Id: I4396d252c5af93e021c9e218dbab7c0e7f190d9d
Reviewed-by: BogDan Vatra <bogdan@kde.org>
Android/LinuxFb: fix QWidget::showFullScreen()

Previously, showFullScreen() had a race condition: it depended
on QFbScreen::setGeometry() being called after the window state was
set (that would trigger QPlatformScreen::resizeMaximizedWindows(), which
was the only part of the code that reacted to WindowFullScreen).
On Android this caused random behaviour.

Task-number: QTBUG-33294
Change-Id: I228e6af4139af1a47387e7d80757d7b46e859580
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
Fix misaligned selection region with text when centered

If the text is centered, the x/y position in the selection QRectF may
be a multiple of 0.5 which is rounded up. This rounding causes
misalignment of the selection region with the text.

The alignment is fixed by using qFloor on the x and y components.

Task-number: QTBUG-34218
Task-number: QTBUG-34234
Change-Id: I4f2fadeb38602f62a93773c6e5faecf03b28069f
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>