hwcontext_opencl: D3D11 to OpenCL mapping

Using cl_khr_d3d11_sharing and cl_intel_d3d11_nv12_media_sharing.

configure

@@ -2120,6 +2120,7 @@ HAVE_LIST="
     $TYPES_LIST
     makeinfo
     makeinfo_html
+    opencl_d3d11
     opencl_dxva2
     opencl_vaapi_beignet
     opencl_vaapi_intel_media
@@ -6172,6 +6173,11 @@ if enabled_all opencl dxva2 ; then
         enable opencl_dxva2
 fi
 
+if enabled_all opencl d3d11va ; then
+    check_type "CL/cl_d3d11.h" clGetDeviceIDsFromD3D11KHR_fn &&
+        enable opencl_d3d11
+fi
+
 enabled vdpau &&
     check_cpp_condition vdpau/vdpau.h "defined VDP_DECODER_PROFILE_MPEG4_PART2_ASP" ||
     disable vdpau