RFR(S) 8148944: CollectorPolicy methods for memory allocations are specific to GenCollectorPolicy

[Mikael Gerdin]

Hi,

Please review this small cleanup to reduce the public API of 
CollectorPolicy.

CollectorPolicy::mem_allocate_work and satisfy_failed_allocation are 
pure virtuals on CollectorPolicy but are only used by 
GenCollectorPolicy/GenCollectedHeap. The other collectors stub the 
methods out with fatal errors if they are called.

My fix is to move the methods to GenCollectorPolicy and let 
GenCollectedHeap access them through its typed pointer to the Gen policy.

I've also taken the opportunity to remove the "virtual" keyword from 
satsfy_failed_metadata_allocation(), it has never been overridden by any 
CollectorPolicy subclass. If that is desirable then it can easily be 
reinstated.

Bug: https://bugs.openjdk.java.net/browse/JDK-8148944
Webrev: http://cr.openjdk.java.net/~mgerdin/8148944/webrev.0/
Testing: Just a local build and testing with GCBasher.

Thanks
/Mikael