Updated git packages fix security vulnerabilities

The updated packages fix security vulnerabilities: The --export-marks option of git fast-import is exposed also via the in-stream command feature export-marks=… and it allows overwriting arbitrary paths. (CVE-2019-1348) When submodules are cloned recursively, under certain circumstances Git could be fooled into using the same Git directory twice. We now require the directory to be empty. (CVE-2019-1349) Recursive clones are currently affected by a vulnerability that is caused by too-lax validation of submodule names, allowing very targeted attacks via remote code execution in recursive clones. (CVE-2019-1387) Arbitrary command execution is possible in Git before before 2.21.1, because a “git submodule update” operation can run commands found in the .gitmodules file of a malicious repository. (CVE-2019-19604)