Use TypePrinter.IntPtrType in CSharpSources.cs code from previous com…

…mit.

(cherry picked from commit 3c31179)

src/Generator/Generators/CSharp/CSharpSources.cs

@@ -1318,7 +1318,7 @@ private bool GenerateVariableGetter(Variable var)
                     ptr = $"*{ptr}";
                     pointerType = pointerType.Pointee.Desugar() as PointerType;
                 }
-                ptr = $"(IntPtr*)({ptr})";
+                ptr = $"({TypePrinter.IntPtrType}*)({ptr})";
             }
 
             var arrayType = var.Type.Desugar() as ArrayType;