RFR: 8353188: C1: Clean up x86 backend after 32-bit x86 removal [v3]

[Aleksey Shipilev]

> Piece-wise cleanup of C1_LIRAssembler_x86, C1_MacroAssembler and related classes. C1 implements the bulk of arch-specific backend there. Major parts of this backend are already removed by #24274, this cleans up another large bulk, and hopefully most of it.
> 
> Additional testing:
>  - [x] Linux x86_64 server fastdebug, `all`
>  - [x] Linux x86_64 server fastdebug, `all` + `-XX:TieredStopAtLevel=1`

Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:

  Minor whitespace reverts

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/24301/files
  - new: https://git.openjdk.org/jdk/pull/24301/files/527854ec..77262978

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24301&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24301&range=01-02

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/24301.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24301/head:pull/24301

PR: https://git.openjdk.org/jdk/pull/24301