oleaut32: Rewrite get_funcdesc to avoid using the funcdesc's oVft member so that it works correctly for non-dual dispinterfaces.

IDirect3DDevice9::ProcessVertices takes a vertex declaration, not a
vertex buffer. The source for ProcessVertices is taken from the
stateblock, not the vertex declaration.

Remove all IWineD3DDevice::SetFVF calls and instead create converted
vertex declarations and use them. The idea is to remove the FVF paths
from wined3d to simplify the code, and optimize the vertex declaration
codepath.