Includes win32 specific extensions definitions when including
`vk_common.hh`. Inside `gpu_context.cc` vulkan needs to be
included before opengl, otherwise windows 10 builders will
report a warning.
```
[6421/7520] Building CXX object source\blender\gpu\CMakeFiles\bf_gpu.dir\intern\gpu_context.cc.obj
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\minwindef.h(130): warning C4005: 'APIENTRY': macro redefinition
C:\Users\blender\git\blender-vexp\blender.git\lib\windows_x64\epoxy\include\epoxy/gl.h(59): note: see previous definition of 'APIENTRY'
```
Pull Request: https://projects.blender.org/blender/blender/pulls/137134
22ae59d28d