Fixed the type of a function to be its original return type.

Signed-off-by: Dimitar Dobrev <dpldobrev@protonmail.com>

src/AST/Function.cs

@@ -258,7 +258,7 @@ namespace CppSharp.AST
             return visitor.VisitFunctionDecl(this);
         }
 
-        public Type Type => ReturnType.Type;
+        public Type Type => OriginalReturnType.Type;
-        public QualifiedType QualifiedType => ReturnType;
+        public QualifiedType QualifiedType => OriginalReturnType;
     }
 }

src/Generator/Generators/CSharp/CSharpSources.cs

@@ -937,7 +937,7 @@ namespace CppSharp.Generators.CSharp
         private void GenerateIndexerSetter(Function function)
         {
             Type type;
-            function.Type.IsPointerTo(out type);
+            function.OriginalReturnType.Type.IsPointerTo(out type);
 
             var @internal = TypePrinter.PrintNative(function.Namespace);
             var ctx = new CSharpMarshalContext(Context)