Migrating to 2.2’s C port API

[Ludovic Courtès]

Hello!

One of the few (only?) things I’ve had to change in C code that uses
libguile and worked fine with 2.0 is code that creates new port types.
This C API has changed incompatibly in 2.2 (the previous one was never
documented):

  
https://www.gnu.org/software/guile/docs/master/guile.html/I_002fO-Extensions.html

I know a couple of projects that use the C port API and will need
“porting” to 2.2 (looking at you GDB and Guile-SSH :-)), so I thought it
might be useful to share what I did for GnuTLS:

  
https://gitlab.com/gnutls/gnutls/commit/27ce47cb2057cbd061b2bbbc03f28a5b1ae72f30

With this change, the GnuTLS bindings work with 2.2, 2.0, and 1.8.

Happy 2.2 hacking!

Ludo’.