i have this in a (hand-written) configure script:

    case "$(uname -s)" in
    Darvin|Linux)
      MAKE=make
      GMAKE=$MAKE
    ;;
    DragonFly|*BSD)
      MAKE=make
      GMAKE=gmake
    ;;
    *)
      MAKE=gmake
      GMAKE=$MAKE
    ;;
    esac

    ...

    if test "$MAKE" != "$GMAKE"; then
      case "$(uname -s)" in
      DragonFly|*BSD)
        populate $rootdir/Makefile.in Makefile
      ;;
      esac
    fi

    cat <<EOF

    to build the programs from their sources:

      $MAKE

    to test their correctness:

      $MAKE check

    EOF

$rootdir/Makefile.in contains

    all .DEFAULT:
      @@GMAKE@ --no-print-directory "$@"