gettext: fix CVE-2018-18751

gettext: fix CVE-2018-18751

Backport patch to fix CVE-2018-18751 for gettext. Because po-gram-gen.y
has been modified by fix-CVE-2018-18751.patch, it requires yacc which
provided by bison-native to re-create po-gram-gen.c. Please remove
bison-native from DEPENDS* when next upgrade.

Ref:
https://security-tracker.debian.org/tracker/CVE-2018-18751

Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>