BoxedWrapper fails for opaque record types

[cameronwhite]

While testing out the 0.5.0-preview.1 release with Pinta, I noticed that value.GetBoxed(Gdk.FileList.GetGType()) is now throwing an exception.

Adding the following code to the OpaqueTypedRecordTest reproduces the same error:

    [TestMethod]
    public void SupportsWrapHandle()
    {
        var recordTester = OpaqueTypedRecordTester.New();

        var wrapped = (OpaqueTypedRecordTester) GObject.Internal.BoxedWrapper.WrapHandle(
                handle: recordTester.Handle.DangerousGetHandle(),
                ownsHandle: false,
                gtype: OpaqueTypedRecordTester.GetGType()
        );

        wrapped.Handle.Should().Be(recordTester.Handle);
    }

Error message:

System.Exception: Type GirTest.OpaqueTypedRecordTester does not define an IntPtr constructor. This could mean improperly defined bindings

It looks like the reflection is failing because opaque records no longer have the constructor signature it's looking for?

[badcel]

Thank you for the report. This should be kept in mind for all kinds of boxed records (opaque / not opaque)

• Test for opaque typedrecord (Fix wrapping opaque typed records #959)
• Test for regular (not opaque) typed record (Support boxed records #965)