Use the latest version of ANGLE

cake/BuildExternals.cake

@@ -395,7 +395,7 @@ Task ("externals-angle-uwp")
     .WithCriteria (!FileExists (ANGLE_PATH.CombineWithFilePath ("uwp/ANGLE.WindowsStore.nuspec")))
     .Does (() =>  
 {
-    var angleVersion = "2.1.10";
+    var angleVersion = "2.1.11";
     var angleUrl = "https://www.nuget.org/api/v2/package/ANGLE.WindowsStore/" + angleVersion;
     var angleRoot = ANGLE_PATH.Combine ("uwp");
     var angleNupkg = angleRoot.CombineWithFilePath ("angle_" + angleVersion + ".nupkg");