d3dx9: Implement point filtering of ARGB surface data in D3DXLoadSurfaceFromMemory

[Tony Wasserka]

- the other filters basically do the same, but the end effect looks
nice, so we can fallback to point filtering for linear, triangle and box
filters for now.
- apparently, D3DERR_INVALIDCALL gets returned if the specified
destination rect exceeds the actual surface boundaries