DERBY-6169: Reduce visibility of classes and methods under impl/sql

- Reduce visibility of fields in ColumnInfo, FKInfo,
  InsertConstantAction and TablePrivilegeInfo to private or package.

- Reduce visibility of TablePrivilegesNode.makePrivilegeInfo() and
  InsertConstantAction.getAutoincRowLocation() to package.

- Clone arrays passed in to public constructors of the above mentioned
  classes as well as ConstraintInfo.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1478295 13f79535-47bb-0310-9956-ffa450edef68