Merge branch 'jk/drop-rsync-transport'

It turns out "git clone" over rsync transport has been broken when
the source repository has packed references for a long time, and
nobody noticed nor complained about it.

* jk/drop-rsync-transport:
transport: drop support for git-over-rsync

diff --cc Documentation/config.txt
Simple merge

diff --cc Documentation/git-clone.txt
Simple merge

diff --cc Documentation/git.txt
Simple merge

diff --cc t/t5510-fetch.sh
Simple merge

diff --cc transport.c
Simple merge