Fix for "Table 'performance_schema.session_variables' doesn't exist"

Author: sodabrew

.travis_mysql57.sh

@@ -9,4 +9,6 @@ apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0x8C718D3B5072
 add-apt-repository 'deb http://repo.mysql.com/apt/ubuntu/ precise mysql-5.7-dmr'
 
 apt-get update
-apt-get -o Dpkg::Options::=--force-confdef -o Dpkg::Options::=--force-confold -y install mysql-server libmysqlclient-dev
+apt-get -o Dpkg::Options::=--force-confdef -o Dpkg::Options::=--force-confnew -y install mysql-server libmysqlclient-dev
+
+mysql_upgrade -u root --force --upgrade-system-tables