Motivation for this change

Adds cairo to environment.noXlibs. If OpenGL support in cairo is enabled without X11, the build fails with:

In file included from /nix/store/5fxfy06brjd1rzga8fdz0ay1ljyv0m4q-libglvnd-1.3.1-dev/include/EGL/egl.h:39,
                 from cairo-gl.h:130,
                 from cairo-gl-private.h:51,
                 from cairo-gl-composite.c:48:
/nix/store/5fxfy06brjd1rzga8fdz0ay1ljyv0m4q-libglvnd-1.3.1-dev/include/EGL/eglplatform.h:128:10: fatal error: X11/Xlib.h: No such file or directory
  128 | #include <X11/Xlib.h>
      |          ^~~~~~~~~~~~
compilation terminated.

Therefore I made glSupport depend on x11Support.

No one maintains cairo, so I'm just pinging people who worked on it recently:
cc @symphorien @matthewbauer @dtzWill

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.