Fix installation of private headers generated by wayland-scanner

Private qtwayland headers were not installed at first build, since
qmake was ignoring unexisting files from the install target. It
required another run of qmake to have a proper Makefile generated.

The rules for generated headers need CONFIG = no_check_exist, so that
files get listed in the Makefile even if they do not exist yet (thanks
to Loïc Yhuel for the pointer).

Change-Id: I1a0278d629295a55a3ddcf5f8fb068a04ba5be47
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Doc: Fix docs for QFontMetrics::height() to match code

After cb8445f0323b0eefbb04f1d8adad81a00b53abd8, Qt no longer
considers the baseline to have a vertical size, so it does
not add an extra pixel to the font height. The documentation
needs to be updated to reflect this.

Task-number: QTBUG-39668
Change-Id: I28fc813e21d73bb03f7055b0f0843511a12d308b
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Correct grammar of missing Q_OBJECT macro warning.

Change-Id: Ifb84220285e38ce6940595035ca9fe012c350b79
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Add that the corner settings are saved/restored with the state

Change-Id: Iee4c04291001470518176d8b3a49c08b52a6336e
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Cocoa: cleanup modal sessions for dialogs not run with .exec()

For modal dialogs not run through QDialog.exec(), the modal sessions
were not cleaned up, causing the application's menus to be inaccessible.

Task-number: QTBUG-37699
Change-Id: I2704c23fec8989aa2e8ddcc3d5e3f21bb6c5db73
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>