Some packages with system package dependencies are broken

[cuihtlauac]

Some Opam packages docs having system package dependencies are broken, I found three of them:

• lablgtk which depends on libgtk2.0-dev see https://ocaml.org/p/lablgtk/2.18.13/doc/index.html
• gammu which depends on libgammu-dev see https://ocaml.org/p/gammu/0.9.4/doc/index.html
• fdkaac which depends on libfdkaac-dev see https://ocaml.org/p/fdkaac/0.3.2/doc/index.html

There's probably more. Additionally, those dependencies are OS/distro dependent. For instance, the three mentioned above are Ubuntu dependencies. Package termbox is not broken although it has a system depency (on Python).

[TheLortex]

• libgtksourceview2.0-dev is available in older releases of debian (<= 10) and ubuntu (<= 20.04)
• libgammu-dev is in bullseye-backports (https://packages.debian.org/bullseye-backports/libgammu-dev)
• libfdkaac-dev is non free

So to fix the three packages a solution is to use debian 10 instead of debian 11, and enable installing non free packages.