patch: fix CVE-2018-6951

patch: fix CVE-2018-6951

* CVE detail: https://nvd.nist.gov/vuln/detail/CVE-2018-6951

* upstream tracking: http://savannah.gnu.org/bugs/?53132

* Fix segfault with mangled rename patch
  - src/pch.c (intuit_diff_type): Ensure that two filenames are specified
    for renames and copies (fix the existing check).

(From OE-Core rev: cdf74e1c67698b2d44a7460ff7d365d6da7b7b96)

Signed-off-by: Jackie Huang <jackie.huang@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>