[lilliput-jdk17u:lilliput] RFR: 8308901: [Lilliput/JDK17] Cherry-pick C2 prototype header improvements

[Aleksey Shipilev]

We need to pick up this improvement from upstream PR to Lilliput/JDK17:
  https://github.com/rkennke/jdk/commit/3a18945ce900e229331b1412002da4a6965e0764

The original hunk here: https://github.com/rkennke/jdk/commit/3a18945ce900e229331b1412002da4a6965e0764#diff-ec810a1df7150822244e55ee309c86d6cbffe108ae9c72b6d258ea5758677c28R2148 -- does not apply to JDK 17u.

Additional testing:
 - [ ] Linux x86_64 fastdebug `tier1`
 - [ ] Linux x86_64 fastdebug `tier1` + `+UseCompactObjectHeaders`

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Commit messages:
 - C2 header improvements

Changes: https://git.openjdk.org/lilliput-jdk17u/pull/27/files
 Webrev: https://webrevs.openjdk.org/?repo=lilliput-jdk17u&pr=27&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8308901
  Stats: 50 lines in 5 files changed: 47 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/lilliput-jdk17u/pull/27.diff
  Fetch: git fetch https://git.openjdk.org/lilliput-jdk17u.git pull/27/head:pull/27

PR: https://git.openjdk.org/lilliput-jdk17u/pull/27