openssl: remove build-time dependency to host perl

[oxalica]

Motivation for this change

The related code is introduced in #50926 (issue: #50921).
But now the perl script c_rehash produced by openssl.bin has shebang #!/usr/bin/env perl, which means we don't need to substitute it anymore.

Removing the occurrence of ${perl} in build script also strip the build-time dependency to host-platform perl, which is actually unused in runtime. This is helpful when cross-compiling openssl, since we don't need to build cross- perl anymore.

Note that this PR produce identical outputs (except hashes) to the current ones.

May fix #19965.

Check build dependencies when cross-compiling:

> nix-store -q --references ${$(nix-instantiate . -A pkgsCross.armv7l-hf-multiplatform.openssl)%%\!*}

Before the PR: (contains perl-5.30.1-armv7l-unknown-linux-gnueabihf)

/nix/store/9krlzvny65gdc8s7kpb6lkx8cd02c25b-default-builder.sh
/nix/store/31qsz0rjknaycs3rrg7kpps9pvxrwg51-bash-4.4-p23.drv
/nix/store/162gc3835iscp0zlmczcj8rchax7132z-openssl-1.1.1d.tar.gz.drv
/nix/store/3xk9ps0qz073k641b88swpa4fgx3hzwg-nix-ssl-cert-file.patch
/nix/store/nh6rsfggyqkaax1xlp57vf2gq09knd1f-perl-5.30.1.drv
/nix/store/s8d2d9lp6ayywfrrxj9rwmzhivz1k9fg-stdenv-linux.drv
/nix/store/j4rai10q3bm89s8bpnf1lwq2200is792-coreutils-8.31-armv7l-unknown-linux-gnueabihf.drv
/nix/store/6vs0w351nnh4la9ica8z50cxjzn7i5c4-perl-5.30.1-armv7l-unknown-linux-gnueabihf.drv
/nix/store/ciwp1yj92pvlyzx0zygv0nr653658pw6-separate-debug-info.sh
/nix/store/lzmcfv2m4ripknpvbsv8wcg1ik1kif4h-use-etc-ssl-certs.patch

After the PR: (perl-arm is gone)

/nix/store/9krlzvny65gdc8s7kpb6lkx8cd02c25b-default-builder.sh
/nix/store/31qsz0rjknaycs3rrg7kpps9pvxrwg51-bash-4.4-p23.drv
/nix/store/11jrn0xjyjs1bf88czk70b5rdjalacgp-openssl-1.1.1d.tar.gz.drv
/nix/store/2apmdnpx75brrrrg3i220x0ff2n8lbj0-stdenv-linux.drv
/nix/store/3xk9ps0qz073k641b88swpa4fgx3hzwg-nix-ssl-cert-file.patch
/nix/store/bqmqj4hj6hs3b73v4z6pi3lnc8gcar3a-perl-5.30.1.drv
/nix/store/ciwp1yj92pvlyzx0zygv0nr653658pw6-separate-debug-info.sh
/nix/store/lzmcfv2m4ripknpvbsv8wcg1ik1kif4h-use-etc-ssl-certs.patch
/nix/store/pli8pmqpj3dwfa70zk69gbnpasgpbm9r-coreutils-8.31-armv7l-unknown-linux-gnueabihf.drv

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
    • openssl
    • pkgsCross.armv7l-hf-multiplatform.openssl

    • with import ./. {
        crossSystem = {
           config = "mips-unknown-linux-musl";
           platform.gcc = { abi = "32"; arch = "mips32r2"; };
        };
      }; openssl

• 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)
  • Identical outputs (except hashes).
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[oxalica]

r? @peti

[gnprice]

May fix #19965.

I think in fact the news is still better than that: I believe #19665 was fixed by the same upstream change that makes this change possible. #19965 (comment)

[oxalica]

ping @peti

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-in-distress/3604/28

[SuperSandro2000]

Got fixed.

[oxalica]

@SuperSandro2000
What is fixed? Sure, the issue I mentioned is fixed. But that's not all of this PR for.

Currently in master, openssl still depends on build-time host-platform perl, but it is actually not used. The c_rehash is using #!/usr/bin/env perl. The related code is not necessary.
I'm building openssl for riscv64. It requires building riscv64 perl while not using it at all. This PR can get rid of it.

[oxalica]

NVM. #115911 did the same thing about 20 days ago. Close as dup.