Motivation for this change

A new major version of libreswan has been released.

Things done

I fixed some of the problems, but not using libreswan myself I lost tuits when encountering the following problem:

../OBJ.linux.x86_64/configs/block -> /nix/store/lvpqg6bqgvpm4ngz47wpwx7khlxj4j58-libreswan-4.1/etc/ipsec.d/policies/block
../OBJ.linux.x86_64/configs/portexcludes.conf -> /nix/store/lvpqg6bqgvpm4ngz47wpwx7khlxj4j58-libreswan-4.1/etc/ipsec.d/policies/portexcludes.conf
mkdir: cannot create directory '/etc/pam.d/': Permission denied
install: cannot create regular file '/etc/pam.d/pluto': No such file or directory
make[2]: *** [Makefile:48: local-install-base] Error 1
make[1]: *** [../mk/targets.mk:73: install-base] Error 2
make[1]: Leaving directory '/build/libreswan-4.1/configs'
make: *** [/build/libreswan-4.1/mk/targets.mk:73: recursive-install-base] Error 2
builder for '/nix/store/i0rfjis0dryp57ibyk4z1h02yg5c0hv7-libreswan-4.1.drv' failed with exit code 2
error: build of '/nix/store/i0rfjis0dryp57ibyk4z1h02yg5c0hv7-libreswan-4.1.drv' failed

This is probably not too hard to fix, but I don't have the time for that.

• 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.