bug#29931: 27.0.50; Slightly suboptimal build behavior on macOS

[Noam Postavsky]

Philipp <p.stephani2@gmail.com> writes:

>   GEN      ../../info/auth.info
> ./../emacs/docstyle.texi:3: warning: unrecognized encoding name `UTF-8'.
>
> This is because macOS ships an ancient version of makeinfo (4.8).

Doesn't configure catch this?

    ## Require makeinfo >= 4.13 (last of the 4.x series) to build the manuals.
    if test "${MAKEINFO:=makeinfo}" != "no"; then
      case `($MAKEINFO --version) 2>/dev/null` in
        *' (GNU texinfo) '4.1[[3-9]]* | \
        *' (GNU texinfo) '[[5-9]]* | \
        *' (GNU texinfo) '[[1-9][0-9]]* ) ;;
        *) MAKEINFO=no;;
      esac
    fi