Upgrade JGit to 4.9.8.201812241815-r
Upgrade JGit to 4.9.8.201812241815-r

This release fixes an issue where AdvertiseRefsHook was not called for
git-upload-pack in protocol v0 bidirectional transports, meaning that
wants aren't validated and a user can fetch anything that is pointed
to by any ref (using fetch-by-sha1), as long as they can guess the
object name.

Bug: Issue 10262
Change-Id: I169fbc742a4edffdf52e6b8ef71b7cd618affa95

GerritCodeReview/gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,GerritCodeReview/gerrit