RFR: 8176472: Lazily create ModuleEntryTable

[Rachel Protacio]

Hello!

Please review this enhancement which moves the unnamed module out of the 
ModuleEntryTable and into the ClassLoaderData so that the MET can be 
lazily created only when other modules are present. The PackageTable 
size has also been updated to be more realistic. These two changes save 
the VM from losing memory space unnecessarily in the module data structures.

Tested with JPRT and RBT tiers 2-5.

Bug: https://bugs.openjdk.java.net/browse/JDK-8176472
Open webrev: http://cr.openjdk.java.net/~rprotacio/8176472.00/

Thank you,
Rachel