The Issue
=======
For a long time now MinGW has been unsupported and unmaintained and at this point,
it looks like something that we should just leave behind and move on.
Why Remove
==========
One of the big motivations for MinGW back in the day is that it was free compared to MSVC which was licensed based.
However, now that this is no longer true we have basically stopped updating the need CMake files.
Along with the CMake files, there are several patches to the extern libs needed to make this work. For example, see:
https://developer.blender.org/diffusion/B/browse/master/extern/carve/patches/mingw_w64.patch
If we wanted to keep MinGW then we would need to make more custom patches to the external libs and
this is not something our platform maintainers are willing to do.
For example, here is the patches needed to build python: https://github.com/Alexpux/MINGW-packages/tree/master/mingw-w64-python3
Fixes T51301
Differential Revision: https://developer.blender.org/D2648
MX (Multiple conteXt) support was dropped from the GLEW 2.0 library to make core profile support cleaner.
Our WITH_GLEW_MX build option was OFF by default already; this commit removes the inactive code paths.
I'm working on a plan for multiple GPUs, contexts, resource sharing, etc. This commit gives us a cleaner starting point for that upcoming work.
Tested on Mac, will test on Linux & Windows immediately after pushing.
