Revert "syscalls/open11.c: Add ifdefs around O_DIRECTORY"

This reverts commit 7d01f97592d9fc5b8735b20960a4462cccfba507.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
open11.c: Define _GNU_SOURCE which is required for O_DIRECTORY

O_DIRECTORY is only available if _GNU_SOURCE is defined
in uClibc toolchains:

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>