RFR: 8350488: [leyden] Experimental AOT-only mode

[Aleksey Shipilev]

There are interesting use cases where we want the AOT-only mode. We can emulate this in current Leyden prototype by relying on preload code, and stopping any profiling, which would naturally lead to no JIT compilations. This would also make interpreter code a bit faster in case we need to fall back there. This mode looks also helpful for studying the compiler dynamics.

Additional testing:
 - [x] Eyeballing compilation logs with `-XX:+PreloadOnly`
 - [ ] Linux x86_64 server fastdebug, `runtime/cds`
 - [ ] Linux x86_64 server fastdebug, `runtime/cds` with `-XX:+PreloadOnly`

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Commit messages:
 - Also do PreloadOnly in other arches template interpreters
 - Fix

Changes: https://git.openjdk.org/leyden/pull/44/files
  Webrev: https://webrevs.openjdk.org/?repo=leyden&pr=44&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8350488
  Stats: 34 lines in 10 files changed: 22 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/leyden/pull/44.diff
  Fetch: git fetch https://git.openjdk.org/leyden.git pull/44/head:pull/44

PR: https://git.openjdk.org/leyden/pull/44