Improve MinGW compilation.
Improve MinGW compilation.

Define D3DCOLORVALUE_DEFINED to avoid a compile
error due to multiple definition of this type
(MinGW header bug when using both D3D9 and D3D11)
and add -pipe.

rdoeffinger/xwa_ddraw_d3d11,rdoeffinger/xwa_ddraw_d3d11