RFR: 8251462: Remove legacy compilation policy [v4]

[Igor Veresov]

> This change removes the legacy compilation policy and an emulation mode to the tiered policy to simulate the old behavior with ```-XX:-TieredCompilation```. The change removed a bunch of interpreter code, devirtualizes the compilation policy API, adds a consistent way to query compiler configuration with the new ```CompilerConfig``` API.
> 
> I've tested this with hs-tier{1,2,3,4,5}. And also made sure it builds and works with C1/C2-Graal/AOT being enabled/disabled.
> 
> Since there are platform-specific changes I would greatly appreciate some help from the maintainers of the specific ports to verify the build and run basic smoke tests. I've already tested x64 and aarch64. Thanks!

Igor Veresov has updated the pull request incrementally with one additional commit since the last revision:

  Check legacy flags validity before deriving flag values for emulation mode.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1985/files
  - new: https://git.openjdk.java.net/jdk/pull/1985/files/dfffc35b..82dffbe9

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1985&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1985&range=02-03

  Stats: 49 lines in 2 files changed: 37 ins; 8 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1985.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1985/head:pull/1985

PR: https://git.openjdk.java.net/jdk/pull/1985