RFR (M): 8035406: Improve data structure for Code Cache remembered sets

[Thomas Schatzl]

Hi all,

  while finalizing another change for review based on this I found a
small bug: the amount of handed out chunks has not been tracked
correctly.

New webrev:
http://cr.openjdk.java.net/~tschatzl/8035406/webrev.3/

Diff to the previous webrev:
http://cr.openjdk.java.net/~tschatzl/8035406/webrev.3.diff/

The only real change is in this hunk:

 void G1CodeRootSet::free_all_chunks(FreeList<G1CodeRootChunk>* list) {
+  G1CodeRootSet::_num_chunks_handed_out -= list->count();
   _free_list.prepend(list);
 }

The remaining 129 additional lines of change contains some new unit
testing code.

Testing:
jprt (also running this test case)

Sorry,
  Thomas