git: security bump to version 2.16.4

git: security bump to version 2.16.4

Forward port of security fixes from the 2.13.7 release. The 2.13.7
release notes say this:

 * Submodule "names" come from the untrusted .gitmodules file, but we
   blindly append them to $GIT_DIR/modules to create our on-disk repo
   paths. This means you can do bad things by putting "../" into the
   name. We now enforce some rules for submodule names which will cause
   Git to ignore these malicious names (CVE-2018-11235).

   Credit for finding this vulnerability and the proof of concept from
   which the test script was adapted goes to Etienne Stalmans.

 * It was possible to trick the code that sanity-checks paths on NTFS
   into reading random piece of memory (CVE-2018-11233).

Cc: Matt Weber <matthew.weber@rockwellcollins.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>