README does not document ocaml-cairo dependency

[gdt]

README.md does not list ocaml-cairo as a dependency, but building without results in an error that cairo2 is missing.

(For background, I am the maintainer of unison and I am trying to untangle what seems to be lablgtk3 depending on ocaml-cairo which is documented to depend on lablgtk2.)

[garrigue]

Indeed, you're right.
We kind of expected everybody to install through opam, which includes the dependency, but we should update the README too.

[gdt]

I use it through pkgsrc, which (as I think all or nearly all other packaging systems do) manages dependencies explicitly, so that there aren't files installed via N different language-specific systems (opam, pip, etc.).

I should have mentioned: cairo2 raises the issue of the other 2 things included from the ocaml-cairo source distribution. I am pretty sure lablgtk does not need them, bit it would be nice if that were clear.

[gdt]

I have just diabled the gtk and pango options in pkgsrc's build of ocaml-cairo.