Deal with awk and gawk on OSX

[douglasnaphas]

I think my mac has old awk installed on it. gensub doesn't work. brew install gawk says:

...
GNU "awk" has been installed as "gawk".
If you need to use it as "awk", you can add a "gnubin" directory
to your PATH from your ~/.bashrc and/or ~/.zshrc like:

    PATH="/opt/homebrew/opt/gawk/libexec/gnubin:$PATH"

Maybe modify the PATH to make gawk available as awk.