coverity#1438784 Uninitialized pointer field

Change-Id: Ic8bc7423765f8610d92ca3ced4c52d4838b7699a
Reviewed-on: https://gerrit.libreoffice.org/59653
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

connectivity/source/drivers/mysqlc/mysqlc_connection.cxx

@@ -64,6 +64,7 @@ void lcl_executeUpdate(MYSQL* pMySql, const rtl::OString& sql)
 
 OConnection::OConnection(MysqlCDriver& _rDriver)
     : OMetaConnection_BASE(m_aMutex)
+    , m_mysql()
     , m_xMetaData(nullptr)
     , m_xDriver(&_rDriver)
 {