grep: add patch to fix CVE-2015-1345

Fixes CVE-2015-1345 - heap buffer overrun.
See https://bugzilla.redhat.com/show_bug.cgi?id=1183651


Patch upstream.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>