RFR: 8268779: ZGC: runtime/InternalApi/ThreadCpuTimesDeadlock.java#id1 failed with "OutOfMemoryError: Java heap space" [v2]

[Per Liden]

> Please review this fix for a ZGC shutdown/abort issue, introduced by JDK-8261759.
> 
> If a GC cycle has aborted, we should not notify that it completed and we should not check for out of memory condition. Doing so can cause pre-mature `OutOfMemoryError`.
> 
> Testing:
>  - Tier 1-7 with ZGC on Linux/x86_64.
>  - Wrote a small reproducer that provokes the problem fairly quickly. With this patch, I can no longer reproduced the issue.

Per Liden has updated the pull request incrementally with one additional commit since the last revision:

  Alternative

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6236/files
  - new: https://git.openjdk.java.net/jdk/pull/6236/files/29035be4..2ee45cb9

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6236&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6236&range=00-01

  Stats: 9 lines in 2 files changed: 3 ins; 2 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6236.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6236/head:pull/6236

PR: https://git.openjdk.java.net/jdk/pull/6236