RFR: 8066771: Refactor VM GC operations caused by allocation failure

[Marcus Larsson]

Hi,

I would like reviews for the following patch, cleaning up and 
refactoring VM GC operations for failed allocations.

Summary:
Different GCs have specialized VM_GC_Operations for collecting due to 
allocation failure. Part of this code is duplicated. The patch adds a 
VM_CollectForAllocation class that removes this duplicated code and 
handles the allocation size and result for such operations. It also 
serves as a common base where tracing can easily be added for these 
operations, regardless of which GC is used.

In addition to the above refactoring, the patch also cleans up around 
the VM GC operations. These changes include:
   * Indentation and whitespace fixes
   * Change 'unsigned int' to 'uint'
   * Change some ints to uint, where it makes more sense
     (gclocker_stalled_count for example)

Webrev:
http://cr.openjdk.java.net/~mlarsson/8066771/webrev.00/

Bug:
https://bugs.openjdk.java.net/browse/JDK-8066771

Testing:
jprt, local jtreg (test/gc)

Thanks,
Marcus