All we need are the APIENTRY and WINGDIAPI macros, as those are used
in the gl.h header. Define those locally for the time we need them.
Use a QT_APIENTRY macro instead of hijacking APIENTRY for when we
declare OpenGL functions with the stdcall calling convention.
A few build fixes needed in tests that used Windows types without
explicitly including windows.h first, or that (incorrectly) included
one of the sub-headers of windows.h (like winuser.h).
[ChangeLog][Potentially Source-Incompatible Changes][OpenGL]
On Windows, the public qopengl.h header no longer includes windows.h.
Pick-to: 6.7
Fixes: QTBUG-120687
Change-Id: I3770ac8eaeee5bcf4e7234e5a2539935a8aa5a7d
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>
b13c610f50