[jdk17u-dev] RFR: 8334769: Shenandoah: Move CodeCache_lock close to its use in ShenandoahConcurrentNMethodIterator

[Aleksey Shipilev]

Semi-clean backport to sync up code bases and make the future backports clean. The change should have no material effect, since it just moves code around. The conflicts are all in copyright years.

Additional testing:
 - [ ] Linux AArch64 server fastdebug, `hotspot_gc_shenandoah`
 - [ ] Linux AArch64 server fastdebug, `tier1` with `-XX:+UseShenandoahGC`

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Commit messages:
 - Backport 4ebb77120af5a4ccbfde63b24cb50e05a3161f16

Changes: https://git.openjdk.org/jdk17u-dev/pull/2742/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2742&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8334769
  Stats: 16 lines in 3 files changed: 3 ins; 8 del; 5 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2742.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2742/head:pull/2742

PR: https://git.openjdk.org/jdk17u-dev/pull/2742