Add DXGI MakeWindowAssociation constants

[Herschel]

Add constants used by IDXGIFactory::MakeWindowAssociation:

#define DXGI_MWA_NO_WINDOW_CHANGES      ( 1 << 0 )
#define DXGI_MWA_NO_ALT_ENTER           ( 1 << 1 )
#define DXGI_MWA_NO_PRINT_SCREEN        ( 1 << 2 )
#define DXGI_MWA_VALID                  ( 0x7 )