Properly set virtual tables up in the internal ctor by pointer.

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

src/Generator/Generators/CSharp/CSharpTextTemplate.cs

@@ -1438,7 +1438,7 @@ namespace CppSharp.Generators.CSharp
 
         private void GenerateVTableClassSetupCall(Class @class)
         {
-            if (@class.IsDynamic && GetUniqueVTableMethodEntries(@class).Count != 0)
+            if (@class.IsDynamic && GetUniqueVTableMethodEntries(@class).Count > 0)
                 WriteLine("SetupVTables();");
         }
 
@@ -1901,41 +1901,39 @@ namespace CppSharp.Generators.CSharp
 
             var hasBaseClass = @class.HasBaseClass && @class.BaseClass.IsRefType;
             if (hasBaseClass)
-                WriteLineIndent(": base(({0}.Internal*) native{1})",
+                WriteLineIndent(": base(({0}.Internal*) null)", QualifiedIdentifierIfNeeded(@class.BaseClass));
-                    QualifiedIdentifierIfNeeded(@class.BaseClass), @class.IsAbstractImpl ? ", true" : string.Empty);
 
             WriteStartBraceIndent();
 
             if (@class.IsRefType)
             {
-                if (shouldGenerateClassNativeField)
+                if (!@class.IsAbstractImpl)
                 {
                     WriteLine("if (native == null)");
                     WriteLineIndent("return;");
+                }
+
                 WriteLine("{0} = new global::System.IntPtr(native);", Helpers.InstanceIdentifier);
                 var dtor = @class.Destructors.FirstOrDefault();
-                    if (dtor != null && dtor.IsVirtual)
+                var hasVTables = @class.IsDynamic && GetUniqueVTableMethodEntries(@class).Count > 0;
+                var setupVTables = !@class.IsAbstractImpl && hasVTables && dtor != null && dtor.IsVirtual;
+                if (setupVTables)
                 {
                     WriteLine("if (skipVTables)");
                     PushIndent();
+                }
+
+                if (@class.IsAbstractImpl || hasVTables)
                     SaveOriginalVTablePointers(@class.Layout.VFTables);
+
+                if (setupVTables)
+                {
                     PopIndent();
                     WriteLine("else");
                     PushIndent();
                     GenerateVTableClassSetupCall(@class);
                     PopIndent();
                 }
-                    else
-                    {
-                        if (@class.IsDynamic && GetUniqueVTableMethodEntries(@class).Count != 0)
-                        {
-                            WriteLine("if (native != null)");
-                            PushIndent();
-                            SaveOriginalVTablePointers(@class.Layout.VFTables);
-                            PopIndent();
-                        }
-                    }
-                }
             }
             else
             {