Fix issue with missing dependency socat when installing MariaDB-galera-server on RedhatEL/OracleEL/(Others?) RPM based

Hi,

One who is trying to install MDBGC using our Repository doesn't install it because it fails, due to socat dependency, and because socat is not provided in the version I tested (Oracle Enterprise Linux 6.6)

If I want to use MDBGC with this OS, I can't, unless I download manually the package

The socat application is not necessary to operate MariaDB Galera Cluster. It is necessary only if you use the optionnal xtrabackup-v2 transfer method
Socat is a dependecy of the percona-xtrabackup package, that one still needs to install manually.

Solutions I see are:

• we put socat in the mariadb repo.
• we install xtrabackup as dependency. At least we fail for something.
• we remove socat dependency.

Thanks in advance,
Joffrey