Motivation for this change

Another round for #43716

Things done

Update/add licenses for:

• data-sharp
• gdcm
• gdk_pixbuf
• geany[-with-vte]
• gengs (dead lownload link, Derivations with dead download links #45076)
• gettext
• giflib_4_1
• ginac
• gio-sharp
• gitlab
• gl117
• glock
• glsurf
• glusterfs
• gnet
• gnuplot
• gnupth
• gnuvd

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• 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 nox --run "nox-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)
• Fits CONTRIBUTING.md.