configure: Require LPDIRECT3DSURFACE9 for dxva2

This fixes dxva2 detection (i.e. correctly realizes that it isn't
available) for WinRT, where dxva2api.h does exist, but these definitions
are omitted (when targeting the API subsets).

Ideally we should rather check for e.g. DXVA2_ConfigPictureDecode,
but configure might fail to find that definition due to _WIN32_WINNT
not being set to the right value during configure. (libavcodec/dxva2.h
manually overrides the _WIN32_WINNT define.)

This allows removing hardcoded --disable-dxva2 from such build
configurations.

Signed-off-by: Martin Storsjö <martin@martin.st>

configure

@@ -1985,7 +1985,7 @@ zmbv_encoder_deps="zlib"
 
 # hardware accelerators
 d3d11va_deps="d3d11_h dxva_h ID3D11VideoDecoder"
-dxva2_deps="dxva2api_h"
+dxva2_deps="dxva2api_h LPDIRECT3DSURFACE9"
 vaapi_deps="va_va_h"
 vda_deps="VideoDecodeAcceleration_VDADecoder_h pthreads"
 vda_extralibs="-framework CoreFoundation -framework VideoDecodeAcceleration -framework QuartzCore"
@@ -4235,6 +4235,7 @@ check_struct "sys/time.h sys/resource.h" "struct rusage" ru_maxrss
 
 check_type "windows.h dxva.h" "DXVA_PicParams_HEVC"
 check_type "windows.h d3d11.h" "ID3D11VideoDecoder"
+check_type d3d9.h LPDIRECT3DSURFACE9
 
 if ! disabled w32threads && ! enabled pthreads; then
     check_func_headers "windows.h process.h" _beginthreadex &&