openssl: prevent -march= flags from being added on mips

[ghost]

Description of changes

Openssl assumes that CFLAGS contains all of the flags that will be passed to the compiler. This assumption fails for nixpkgs due to our cc-wrapper.

On mips platforms, openssl scans CFLAGS to see if the user passed a -march flag; if not, it adds its own:

  if ($target =~ /linux.*-mips/ && !$disabled{asm}
        && !grep { $_ =~ /-m(ips|arch=)/ } (@{$config{CFLAGS}})) {
        # minimally required architecture flags for assembly modules
        my $value;
        $value = '-mips2' if ($target =~ /mips32/);
        $value = '-mips3' if ($target =~ /mips64/);
        unshift @{$config{cflags}}, $value;
        unshift @{$config{cxxflags}}, $value if $config{CXX};
  }

Unfortunately since nixpkgs adds -march= in the wrapper, rather than the CFLAGS, openssl can't see it. The result is two conflicting -march= flags and a build failure when the user has customized hostPlatform.gcc.arch:

  openssl-mips64el-unknown-linux-gnuabin32> mips64el-unknown-linux-gnuabin32-gcc  -I. -Iinclude -Iapps/include  -fPIC -pthread -mabi=n32 -mips3 -Wa,--noexecstack -Wall -O3 -DOPENSSL_USE_NODELETE -DOPENSSL_PIC -DOPENSSLDIR="\"/nix/store/8kwvrgwdk56ml6sz5swr71fv9mv4592w-openssl-mips64el-unknown-linux-gnuabin32-3.0.9/etc/ssl\"" -DENGINESDIR="\"/nix/store/8kwvrgwdk56ml6sz5swr71fv9mv4592w-openssl-mips64el-unknown-linux-gnuabin32-3.0.9/lib/engines-3\"" -DMODULESDIR="\"/nix/store/8kwvrgwdk56ml6sz5swr71fv9mv4592w-openssl-mips64el-unknown-linux-gnuabin32-3.0.9/lib/ossl-modules\"" -DOPENSSL_BUILDING_OPENSSL -DNDEBUG  -MMD -MF apps/lib/libapps-lib-engine.d.tmp -MT apps/lib/libapps-lib-engine.o -c -o apps/lib/libapps-lib-engine.o apps/lib/engine.c
  cc1: error: '-mips3' conflicts with the other architecture options, which specify a mips64r2 processor
  cc1: error: '-mips3' conflicts with the other architecture options, which specify a mips64r2 processor
  make[1]: *** [Makefile:4254: apps/lib/libapps-lib-app_libctx.o] Error 1
  make[1]: *** Waiting for unfinished jobs....
  make[1]: *** [Makefile:4262: apps/lib/libapps-lib-app_params.o] Error 1
  make[1]: *** [Makefile:4270: apps/lib/libapps-lib-app_provider.o] Error 1

This commit defeats the perl code above by passing CFLAGS=-march to openssl's ./Configure script.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 23.11 Release Notes (or backporting 23.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.