RFR: 8344260: GenShen: Excess unaffiliated regions reserved for old will not be transferred to young

[William Kemper]

Accidental assignment to new (and unread) variable.

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Commit messages:
 - Fix to have excess unaffiliated old regions transferred to young

Changes: https://git.openjdk.org/shenandoah/pull/538/files
  Webrev: https://webrevs.openjdk.org/?repo=shenandoah&pr=538&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344260
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/shenandoah/pull/538.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/538/head:pull/538

PR: https://git.openjdk.org/shenandoah/pull/538