regex: avoid glibc deadlock during configure glibc has a known bug where certain corruptions of the heap can cause malloc to default to printing a debug message that includes a backtrace, but the act of getting the backtrace uses dlopen which in turn calls into malloc, causing a recursive lock ending in deadlock. Thus, when configure is probing for a known glibc heap corruption bug, the overall configure would hang. The solution suggested by glibc developers is to force malloc to quit printing debug messages, which avoids recursive malloc. * m4/regex.m4 (gl_REGEX): Avoid recursive malloc deadlock when glibc bug 15078 in turn triggers bug 16159. Reported by Michal Privoznik. Signed-off-by: Eric Blake <eblake@redhat.com>

# fegetround.m4 serial 1
dnl Copyright (C) 2011-2013 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_FEGETROUND],
[
  dnl Determine FEGETROUND_LIBM.
  gl_MATHFUNC([fegetround], [int], [(void)], [#include <fenv.h>])
  if test $gl_cv_func_fegetround_no_libm = no \
     && test $gl_cv_func_fegetround_in_libm = no; then
    HAVE_FEGETROUND=0
  else
    HAVE_FEGETROUND=1
    AC_DEFINE([HAVE_FEGETROUND], [1],
      [Define to 1 if you have the 'fegetround' function.])
  fi
  AC_SUBST([FEGETROUND_LIBM])
])