glibc/sysdeps/mach/hurd/configure.in

sinclude(./aclocal.m4)dnl Autoconf lossage.
GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.

# GNU libc on the Hurd is always reentrant.
DEFINES="$DEFINES -D_LIBC_REENTRANT"

# Don't bother trying to generate any glue code to be compatible with the
# existing system library, because we are the only system library.
inhibit_glue=yes

if test "x$prefix" != x; then
  AC_MSG_WARN([--prefix= (empty) is required for GNU/Hurd to work normally])
fi

case "$machine" in
  i386*)
    # With --enable-libio, the default oldest ABI is 2.5.5;
    # without --enable-libio, the default oldest ABI is 2.0.
    # We only need a "yes" here if the oldest ABI supported will be < 2.2.5.
    if if test "$stdio" = libio; then
         test "$oldest_abi" != default && test "$oldest_abi" \< "2.2.5"
       else
         test "$oldest_abi" = default || test "$oldest_abi" \< "2.2.5"
       fi; then
      libc_cv_gcc_unwind_find_fde=yes
    fi
    ;;
esac