Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56910
-1 is not a supported option for maxConnections with the APR connector so don't allow it.
Also prevent updates while the connector is running which is also unsupported.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1622713 13f79535-47bb-0310-9956-ffa450edef68