Install the correct mysql-dev package for RHEL6

RHEL6/CentOS6 requires mysql-devel/mysql-lib packages instead of
libmysqlclient-dev for 'mysql-dev' element.

Change-Id: If5a004720b5982949568e5f79b887b9d5202a576
Closes-Bug: #1393313
Merge "Install the correct mysql-dev package for RHEL6"