[Development] Header review for 5.7.0 (vs 5.6.1)

[Edward Welbourne]

Following up on the earlier header review, comparing 5.6 to 5.7, I've
now prepared a review of 5.7.0 vs 5.6.1, following some moderate
refinements to the scripts.  Hopefully various "not yet merged" changes
are now in 5.7.0 to fix blemishes noticed in the earlier review:

https://codereview.qt-project.org/160661 – qtbase
https://codereview.qt-project.org/160662 – qtdeclarative
https://codereview.qt-project.org/160663 – qtactiveqt
https://codereview.qt-project.org/160664 – qtmultimedia
https://codereview.qt-project.org/160665 – qttools
https://codereview.qt-project.org/160666 – qtlocation
https://codereview.qt-project.org/160667 – qtconnectivity
https://codereview.qt-project.org/160668 – qtwayland
https://codereview.qt-project.org/160669 – qt3d (which no-one reviewed last time)
https://codereview.qt-project.org/160670 – qtquickcontrols
https://codereview.qt-project.org/160671 – qtserialport
https://codereview.qt-project.org/160672 – qtx11extras
https://codereview.qt-project.org/160673 – qtandroidextras
https://codereview.qt-project.org/160674 – qtwebsockets
https://codereview.qt-project.org/160675 – qtwebengine
https://codereview.qt-project.org/160676 – qtcanvas3d
https://codereview.qt-project.org/160677 – qtquickcontrols2

The git show output of all of these taken together comes to a little
under 29k lines; the boring diff (that's been elided here; I eye-balled
it to check it really was boring) totalled about 150k lines.

If there are any parts of these reviews that are boring and that can be
characterised straightforwardly (i.e. such that a dumb script can
implement them reliably), please do mention them on the bug report [0]
or point out in the code review [1] how to implement them.

[0] https://bugreports.qt.io/browse/QTQAINFRA-973
[1] https://codereview.qt-project.org/157299

Please take a look at the modules you care about and point out anything
that's going to cause problems for the usual compatibility constraints,

        Eddy.