[jdk17u-dev] RFR: 8329570: G1: Excessive is_obj_dead_cond calls in verification

[Aleksey Shipilev]

Unclean backport to improve fastdebug build performance, which improves testing. The code shape in JDK 17 is different, I reapplied the hunks in places relevant to JDK 17.

Additional testing:
 - [ ] GHA

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Commit messages:
 - Backport 29992e1fca4faef0fe0ac453c7e78db4628d5e70

Changes: https://git.openjdk.org/jdk17u-dev/pull/2425/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2425&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329570
  Stats: 6 lines in 1 file changed: 2 ins; 4 del; 0 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2425.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2425/head:pull/2425

PR: https://git.openjdk.org/jdk17u-dev/pull/2425