Enable Anisotropic filtering in ES.

This adds a check to make sure the vendor supports anisotropic filtering.
Pretty much all vendors support this, even the mobile ones.

Source/Core/VideoBackends/OGL/Render.h

@@ -52,6 +52,7 @@ struct VideoConfig
 	bool bSupports3DTextureStorage;
 	bool bSupportsEarlyFragmentTests;
 	bool bSupportsConservativeDepth;
+	bool bSupportsAniso;
 
 	const char* gl_vendor;
 	const char* gl_renderer;