RFR: 8329332: Remove CompiledMethod and CodeBlobLayout classes

[Vladimir Kozlov]

Revert [JDK-8152664](https://bugs.openjdk.org/browse/JDK-8152664) RFE [changes](https://github.com/openjdk/jdk/commit/b853eb7f5ca24eeeda18acbb14287f706499c365) which was used for AOT [JEP 295](https://openjdk.org/jeps/295) implementation in JDK 9. The code was left in HotSpot assuming it will help in a future. But during work on Leyden we decided to not use it. In Leyden cached compiled code will be restored in CodeCache as normal nmethods: no need to change VM's runtime and GC code to process them.

I may work on optimizing `CodeBlob` and `nmethod` fields layout to reduce header size in separate changes. In these changes I did simple fields reordering to keep small (1 byte) fields together.

I do not see (and not expected) performance difference with these changes.

Tested tier1-5, xcomp, stress. Running performance testing.

I need help with testing on platforms which Oracle does not support.

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Commit messages:
 - remove trailing whitespace
 - 8329332: Remove CompiledMethod and CodeBlobLayout classes

Changes: https://git.openjdk.org/jdk/pull/18554/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18554&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329332
  Stats: 3885 lines in 118 files changed: 1281 ins; 1723 del; 881 mod
  Patch: https://git.openjdk.org/jdk/pull/18554.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18554/head:pull/18554

PR: https://git.openjdk.org/jdk/pull/18554