[patch] allow darwin as cross compile host

[Andrew Cagney]

BTW, digging around I found:

case "${host}" in

*-*-nextstep*)          gdb_host=nextstep ;;
*-apple-rhapsody*)      gdb_host=rhapsody ;;
*-apple-macos10*)       gdb_host=macosx ;;
*-apple-darwin*)        gdb_host=macosx ;;

Andrew