rsync: security bump to version 3.1.2

Fixes:
Make sure that all transferred files use only path names from inside the
transfer.  This makes it impossible for a malicious sender to try to
make the receiver use an unsafe destination path for a transferred file,
such as a just-sent symlink.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>