Reviewed-by: brutisso, tschatzl

Summary: Replace G1CodeRootSet with a Hashtable based implementation, merge Code Root Migration phase into Code Root Scanning
Reviewed-by: jmasa, brutisso, tschatzl

Summary: Changed the use of %d to SIZE_FORMAT macro in format string when printing size_t values.
Reviewed-by: stefank, ehelin

8025441: G1: assert "assert(thread < _num_vtimes) failed: just checking" fails when G1ConcRefinementThreads > ParallelGCThreads
Summary: The initialization for the remembered set summary data structures used the wrong thread count, i.e. number of worker threads instead of number of refinement threads.
Reviewed-by: brutisso

Summary: Add memory consumption breakdown on a per region type in the G1 remembered set summary statistics. This simplifies remembered set memory consumption analysis.
Reviewed-by: brutisso

Summary: Add a list of nmethods to the RSet for a region that contain references into the region. Skip scanning the code cache during root scanning and scan the nmethod lists during RSet scanning instead.
Reviewed-by: tschatzl, brutisso, mgerdin, twisti, kvn

Summary: Fixed the output of G1SummarizeRSetStats: too small datatype for the number of concurrently processed cards, added concurrent remembered set thread time retrieval for Linux and Windows (BSD uses os::elapsedTime() now), and other cleanup. The information presented during VM operation is now relative to the previous output, not always cumulative if G1SummarizeRSetStatsPeriod > 0. At VM exit, the code prints a cumulative summary.
Reviewed-by: johnc, jwilhelm