WMF: enabled HW-accelerated video decoding for the QML video item.

It also applies to QGraphicsVideoItem when used on a GL viewport.
We now have a new video sink that is based on Microsoft's EVR sink, we just
replace the default Presenter with our own. Frames are rendered into D3D
surfaces using DXVA, then copied into a shared D3D/EGL surface and finally
bound to a GL texture to be used by the video surface.
The shared D3D/EGL surface is a feature provided by ANGLE and therefore Qt
must be compiled with ANGLE for this new video sink to be compiled and
used.

Change-Id: I0b7b9968eed5488f9ef1a2dcca5213bd0af232ab
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>

src/imports/multimedia/qsgvideonode_texture.cpp

@@ -118,6 +118,7 @@ protected:
         "    gl_FragColor = texture2D(rgbTexture, qt_TexCoord) * opacity;"
         "}";
 
+#ifndef QT_OPENGL_ES_2_ANGLE
         static const char *colorsSwapShader =
         "uniform sampler2D rgbTexture;"
         "uniform lowp float opacity;"
@@ -137,6 +138,9 @@ protected:
             default:
                 return shader;
         }
+#else
+        return shader;
+#endif
     }
 
     virtual void initialize() {