libc_add_on_frag=$libc_add_on_srcdir/configure
    libc_add_on_canonical=
    libc_add_on_config_subdirs=
    if test -r "$libc_add_on_frag"; then
      { $as_echo "$as_me:${as_lineno-$LINENO}: running configure fragment for add-on $libc_add_on" >&5
$as_echo "$as_me: running configure fragment for add-on $libc_add_on" >&6;}
	libc_add_on_canonical=unknown
      	libc_add_on_subdirs=
      	. "$libc_add_on_frag"
      	test -z "$libc_add_on" || {
		configured_add_ons="$configured_add_ons $libc_add_on"
	if test "x$libc_add_on_canonical" = xunknown; then
	  as_fn_error $? "fragment must set \$libc_add_on_canonical" "$LINENO" 5
	fi