'use threads' in Perl

Having need of a more featureful scanning/ocr program I made a port of 
gscan2pdf (https://gscan2pdf.sourceforge.net) but it seems this is a 
no-go because it uses threads, and our Perl build does not have threads 
enabled.

Oh well. No doubt there is a good reason, as always.

However, to make this draft port I had to make the following new ports:

- x11/goocanvas canvas widget for GTK+ using Cairo

- graphics/p5-Image-Sane Perl extension for SANE

- textproc/p5-PDF-Builder creation and modification of PDF files

- x11/p5-GooCanvas2 binding for GooCanvas2+

- x11/p5-Gtk3-SimpleList simple interface to Gtk3's complex MVC list widget

Is there interest in merging any of these, in which case I can send to 
the list?

Chris