[Mono.Android] Don't optimize URL encoding (#1001)

Fixes: https://bugzilla.xamarin.com/show_bug.cgi?id=60473

In the case when the URL doesn't contain any query elements we
optimized for speed and memory by not using `UrlBuilder` to do the
encoding work on the URL. However, it causes problems with URLs
that are sent pre-encoded.

Remove the optimization and rely on `UrlBuilder` in all cases.

Author: grendello

src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs

@@ -207,9 +207,6 @@ string EncodeUrl (Uri url)
 			if (url == null)
 				return String.Empty;
 
-			if (String.IsNullOrEmpty (url.Query))
-				return Uri.EscapeUriString (url.ToString ());
-
 			// UriBuilder takes care of encoding everything properly
 			var bldr = new UriBuilder (url);
 			if (url.IsDefaultPort)