thirdparty/directxtex: Import DirectXTex library.

Will be useful for converting DirectX image formats.
directxtex: Build with cmake.
directxtex: Don't redefine NOMINMAX.
directxtex: Fix include filename case.
directxtex: Get it building on MinGW.
d3d11state: Use DirectXTex for format conversion.
Merge branch 'directxtex'
d3dretrace: Use DirectXTex for d3d10 state too.