[krita/krita/3.3] /: Merge branch 'alvin/T6976-angle-3.3' into krita/3.3

[Alvin Wong]

Git commit 5bcb3b2dbb78108caed24a5b311e73e4c389b95b by Alvin Wong.
Committed on 12/09/2017 at 13:14.
Pushed by alvinwong into branch 'krita/3.3'.

Merge branch 'alvin/T6976-angle-3.3' into krita/3.3

This adds canvas rendering with Direct3D11 via ANGLE on Windows.

ANGLE is a library which translates OpenGL ES rendering functions to
other hardware rendering APIs, including Direct3D. It is supported by
the Windows build of Qt.

This aims to improve the compatibility of the OpenGL canvas with buggy
Windows Intel drivers by allowing the use of the Direct3D11 rendering
backend of ANGLE.

Krita can still be used with a Qt build without dynamic OpenGL support,
but it will only be able to use native desktop OpenGL. To enable ANGLE,
`ext_qt` will need to be rebuilt. `ext_qt` target on Windows is also
upgraded to Qt 5.9.1, and to build it with ANGLE properly one would need
to use mingw-w64 7.1 and have Windows 10 SDK installed.

CCMAIL: kimageshop at kde.org
CCBUG: 360601
Maniphest Tasks: T5883, T6696, T6728, T6976


https://commits.kde.org/krita/5bcb3b2dbb78108caed24a5b311e73e4c389b95b