RFR: 8366811: [leyden] Expose nmethod AOT entry in VMStructs

[Aleksey Shipilev]

This is needed for external tools like async-profiler to disambiguate the frames that are executed with nmethod from AOT.  I have an async-profiler branch that is able to access this and give us interesting flamegraphs. So I am sure this thing works.

Additional testing:
 - [x] Linux x86_64 server fastdebug, `runtime/cds`

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Commit messages:
 - Fix builds
 - Fix

Changes: https://git.openjdk.org/leyden/pull/94/files
  Webrev: https://webrevs.openjdk.org/?repo=leyden&pr=94&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8366811
  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/leyden/pull/94.diff
  Fetch: git fetch https://git.openjdk.org/leyden.git pull/94/head:pull/94

PR: https://git.openjdk.org/leyden/pull/94