[jdk17u-dev] RFR: 8271118: C2: StressGCM should have higher priority than frequency-based policy

[Aleksey Shipilev]

Clean backport to greatly extend the scope of `StressGCM`. This would allow better compiler testing, including test backports (which rely on `StressGCM` with given seed to reproduce sometimes), and jcstress runs (which automatically opts in to `StressGCM`).

There seem to be a bunch of compiler bugfixes found/triggered by wider scope, recorded as related issues in duplicate [JDK-8257146](https://bugs.openjdk.org/browse/JDK-8257146), all of which are resolved in current 17u.

Additional testing:
 - [x] macos-aarch64-server-fastdebug, `hotspot:tier1`
 - [ ] linux-aarch64-server-fastdebug, `tier{1,2,3}` with `-XX:+StressGCM`
 - [ ] linux-x86_64-server-fastdebug, `tier{1,2,3}` with `-XX:+StressGCM`

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Commit messages:
 - Backport ed1cb24027f48ec8e243c26e1847561fa902d91f

Changes: https://git.openjdk.org/jdk17u-dev/pull/2038/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2038&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8271118
  Stats: 52 lines in 2 files changed: 38 ins; 10 del; 4 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2038.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2038/head:pull/2038

PR: https://git.openjdk.org/jdk17u-dev/pull/2038