direct3d9: link with dxva2.lib

The Direct3D9 code is enabled for non-UWP targets and all Windows targets
have this DLL (since Vista).
DXVAHD_CreateDevice is available since Windows 7 [^1].
If for some reason the DLL is not there, the plugin won't be loaded
and it will rightfully be skipped.

[^1]: https://learn.microsoft.com/en-us/windows/win32/api/dxvahd/nf-dxvahd-dxvahd_createdevice