[generator] Remove unnecessary code. (#1730)

Generator diff: https://gist.github.com/rolfbjarne/f6c0e32960eacbafd38238e623d3321a

src/Foundation/NSString.cs

@@ -88,11 +88,6 @@ namespace XamCore.Foundation {
 
 		public static readonly NSString Empty = new NSString (String.Empty);
 
-#if GENERATOR && !MONOMAC
-		public NSString (IntPtr handle) : base (handle) {
-		}
-#endif
-
 		internal NSString (IntPtr handle, bool alloced) : base (handle, alloced)
 		{
 		}

src/btouch.cs

@@ -39,8 +39,6 @@ using XamCore.Foundation;
 using Xamarin.Utils;
 
 class BindingTouch {
-	static Type CoreObject = typeof (XamCore.Foundation.NSObject);
-
 	static TargetFramework? target_framework;
 	public static PlatformName CurrentPlatform;
 	public static bool Unified;
@@ -422,7 +420,6 @@ class BindingTouch {
 
 			var g = new Generator (nsManager, public_mode, external, debug, types.ToArray (), strong_dictionaries.ToArray ()){
 				BindThirdPartyLibrary = BindingThirdParty,
-				CoreNSObject = CoreObject,
 				BaseDir = basedir != null ? basedir : tmpdir,
 				ZeroCopyStrings = zero_copy,
 				InlineSelectors = inline_selectors,