package/qt5/qt5webkit: bump to version 5.212.0-alpha4

Switch to latest release in new active upstream:
https://github.com/qtwebkit/qtwebkit



Migrate python2 build to python3.

Drop patches that are upstream/no longer needed.

Adapt/add patches to fix build issues.

Rework build system to use cmake instead of qmake(which does not
currently support cross compilation).

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>