The PETSc library's config/install.py script checks whether
/usr/bin/install_name_tool is an existing file:

https://gitlab.com/petsc/petsc/-/blob/master/config/install.py#L368

Therefore, it is not enough to replace it with something that we expect
to be on the PATH, as this will cause the linked if statement to be
silently skipped. The consequence is that applications linked against
this version of petsc will fail at runtime on MacOS with a dynamic
loading error.

Instead, we should replace install_name_tool with the absolute path of a
binary we know will be present at build time.

Note that this should be fixed upstream as well, but this is sufficient
to fix the runtime error.

Motivation for this change

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.