Install link to mysql unix socket

Default mysql socket for Fedora/RHEL mysql client lib is
/var/lib/mysql/mysql.sock.  Although we change this path in a mysql
config file, it's not sufficient because some clients don't read any
mysql config and just use default socket path.

For Fedora/RHEL this patch installs a link at the origional path.

Change-Id: Id46961278c9d33d04d555f14d8334c5fe2cb23c7
Merge "Install link to mysql unix socket"