RFR: 8312610: GenShen: Old generation available is unintentionally restricted by mutator's available memory [v2]

[William Kemper]

> Only young gen allocations should be restricted to memory in the mutator's view of the freeset.

William Kemper has updated the pull request incrementally with one additional commit since the last revision:

  Restore single-generation computation of "soft" available

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

Changes:
  - all: https://git.openjdk.org/shenandoah/pull/301/files
  - new: https://git.openjdk.org/shenandoah/pull/301/files/9a002b1d..0df69803

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=shenandoah&pr=301&range=01
 - incr: https://webrevs.openjdk.org/?repo=shenandoah&pr=301&range=00-01

  Stats: 9 lines in 2 files changed: 9 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/shenandoah/pull/301.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/301/head:pull/301

PR: https://git.openjdk.org/shenandoah/pull/301