What is GLIBCXX_ENABLE_PARALLEL for?

[Jonathan Wakely]

acinclude.m4 has:

dnl
dnl Check for parallel mode pre-requisites, including OpenMP support.
dnl
dnl  +  Usage:  GLIBCXX_ENABLE_PARALLEL
dnl
AC_DEFUN([GLIBCXX_ENABLE_PARALLEL], [

  enable_parallel=no;

  # See if configured libgomp/omp.h exists. (libgomp may be in
  # noconfigdirs but not explicitly disabled.)
  if echo " ${TARGET_CONFIGDIRS} " | grep " libgomp " > /dev/null 2>&1 ; then
    enable_parallel=yes;
  else
    AC_MSG_NOTICE([target-libgomp not built])
  fi

  AC_MSG_CHECKING([for parallel mode support])
  AC_MSG_RESULT([$enable_parallel])
])

Which is called from configure.ac (with an unused argument):

GLIBCXX_ENABLE_PARALLEL([yes])

What's the point?

It doesn't seem to have any side effects except printing some messages
while configure runs, it doesn't actually enable or disable anything.