Reduce visibility of constructors.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1624568 13f79535-47bb-0310-9956-ffa450edef68
Remove unused ConstantPool.constantToString methods.
Found thanks to Cobertura coverage report.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1624569 13f79535-47bb-0310-9956-ffa450edef68