git: upgraded package to upstream

Upgraded dev-vcs/git to version 2.21.0 on amd64

BUG=chromium:991071, chromium:1106153
TEST=Built package for an overlay that has a CROS_WORKON_COMMIT

Change-Id: I5474926aa39ddcbadd9f4c38b02d9ab529a943e9
Reviewed-on: https://chromium-review.googlesource.com/1737170
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2341655
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2341894
(cherry picked from commit a84e6835d9a126a66806ff20ff468bc50e230f61)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2341999
(cherry picked from commit 81512f7da9eb14714d85e21f1c68a8ce1ae65345)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2340777
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2342649
(cherry picked from commit 401beebb2e02e4ad774c4e6dd08b43f40b6cfcd2)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2342691
(cherry picked from commit 4f5ca131ed132515473ed5b66c5a480b16031ad0)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2349233
6 files changed