RFR: Generation labeling for regions and allocation requests. [v2]

[Bernd Mathiske]

> The original generational Shenandoah patch authored by Roman Kennke. 
> The rest of the project will build upon this base.

Bernd Mathiske has updated the pull request incrementally with one additional commit since the last revision:

  Simplify forwarding conditional in evacuation.

-------------

Changes:
  - all: https://git.openjdk.java.net/shenandoah/pull/6/files
  - new: https://git.openjdk.java.net/shenandoah/pull/6/files/b90f4dc9..26ae8b70

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=shenandoah&pr=6&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=shenandoah&pr=6&range=00-01

  Stats: 10 lines in 1 file changed: 1 ins; 5 del; 4 mod
  Patch: https://git.openjdk.java.net/shenandoah/pull/6.diff
  Fetch: git fetch https://git.openjdk.java.net/shenandoah pull/6/head:pull/6

PR: https://git.openjdk.java.net/shenandoah/pull/6