PreparedStatements may not be closed when using prepared statement caching

When using JBoss' prepared statement caching the use of java.sql.PreparedStatement#close() must not occur multiple times as this may lead to the original prepared statements not being closed. Within our project a SQLException generated by Oracle concerning running out of open cursors is thrown.

The origin of this bug is org.jboss.resource.adapter.jdbc.CachedPreparedStatement where the "inUse" member can get a value less than 0. If this happens the original prepared statement is not closed within #ageOut() although it should be.