RFR: 8353192: C2: Clean up x86 backend after 32-bit x86 removal [v2]

[Aleksey Shipilev]

> Piece-wise cleanup of C2 x86 backend. C2_MacroAssembler, x86.ad and related files are the target for this cleanup. 
> 
> Additional testing:
>  - [x] Linux x86_64 server fastdebug, `all`
>  - [x] Linux x86_64 server fastdebug, `all` + `-XX:-TieredCompilation`

Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Cleanup ADLC as well
 - Revert some accidental removals
 - Merge branch 'master' into JDK-8353192-x86-c2-backend
 - Touchup
 - Fix

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/24300/files
  - new: https://git.openjdk.org/jdk/pull/24300/files/6edebc7b..5d0c852e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24300&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24300&range=00-01

  Stats: 29291 lines in 725 files changed: 19768 ins; 7520 del; 2003 mod
  Patch: https://git.openjdk.org/jdk/pull/24300.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24300/head:pull/24300

PR: https://git.openjdk.org/jdk/pull/24300