peti_silent_mode

Temporarily disable console output. For example:

   PETI_SILENT_MODE(on)    dnl be silent
   AC_PROG_CXX
   PETI_SILENT_MODE(off)   dnl talk to me again
   AC_PROG_RANLIB

Many thanks to Paolo Bonzini for proposing this macro.

AC_DEFUN([PETI_SILENT_MODE],
  [
  case "$1" in
    on)
      exec 6>/dev/null
      ;;
    off)
      exec 6>&1
      ;;
    *)
      AC_MSG_ERROR(Silent mode can only be switched "on" or "off".)
      ;;
  esac
  ])dnl