Also some patches to address comments made on the last MR. :)
-- v2: d3dx9: Add support for loading non-square cubemap DDS files into cube textures. d3dx9: Add support for specifying which array layer to get pixel data from to d3dx_image_get_pixels(). d3dx9: Use d3dx_image structure inside of D3DXCreateCubeTextureFromFileInMemoryEx(). d3dx9: Cleanup texture value argument handling in D3DXCreateCubeTextureFromFileInMemoryEx(). d3dx9: Refactor texture creation and cleanup in D3DXCreateCubeTextureFromFileInMemoryEx(). d3dx9/tests: Add more D3DXCreateCubeTextureFromFileInMemory{Ex}() tests. d3dx9/tests: Reorder test structure members. d3dx9/tests: Make some test structures static const.