After this there is one more set of patches to finish up the file saving functions, I split it into two to hopefully make it easier to review. :)
-- v2: d3dx9: Use D3DXSaveVolumeToFileInMemory() inside of D3DXSaveTextureToFileInMemory(). d3dx9: Implement D3DXSaveVolumeToFile{A,W,InMemory}(). d3dx9/tests: Add tests for D3DXSaveVolumeToFile{A,W,InMemory}(). d3dx9: Add stubs for D3DXSaveVolumeToFile{A,W,InMemory}().