Fix mysql module so it can work w/out mariadb

Previously this had "require => true" which is meaningless
and causes a dramatic puppet failure without a line #.  What
we want is 'undef' which just means it requires nothing.

Change-Id: I8d8bccc54f86b5df02180fb7c7d30f97fc5596a5
Merge "Fix mysql module so it can work w/out mariadb" into production