RFR: Improve evacuation instrumentation

[William Kemper]

This change adds instrumentation to reveal the following:
* How many bytes were evacuated by gc workers and mutators
* How many bytes were abandoned due to evacuation races
* The age of survivors
* The break down of targets for evacuation in the collection set

The implementation is based on a new thread local structure to track and aggregate these statistics.

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Commit messages:
 - Fix whitespace
 - Use initial tenuring threshold when printing region ages
 - Factor promotion failure reporting into its own method
 - Merge branch 'shenandoah-master' into evacuation-instrumentation
 - Clarify log messages and add more detail
 - Fix confusing heuristic log message
 - Message formatting fix
 - WIP: Include age table for evacuated objects and regions
 - WIP: Finish thread local model
 - WIP: Adapt to thread local model
 - ... and 5 more: https://git.openjdk.org/shenandoah/compare/50c54581...201e8610

Changes: https://git.openjdk.org/shenandoah/pull/167/files
 Webrev: https://webrevs.openjdk.org/?repo=shenandoah&pr=167&range=00
  Stats: 423 lines in 14 files changed: 323 ins; 71 del; 29 mod
  Patch: https://git.openjdk.org/shenandoah/pull/167.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah pull/167/head:pull/167

PR: https://git.openjdk.org/shenandoah/pull/167