RFR: 8351162: Clean up x86 (Macro)Assembler after 32-bit x86 removal [v2]

[Aleksey Shipilev]

> This improvement targets x86 `(Macro)Assembler`. We are mostly cleaning up `LP64` predicated code blocks, and a bit of related code.
> 
> It is enticing to remove all `*ptr` methods, and rename all uses from `*ptr` to `*q`, but that turns out to be very intrusive. That is left for a future RFE, if we ever consider doing it.
> 
> Additional testing:
>  - [x] Linux x86_64 server fastdebug, `all`

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 three additional commits since the last revision:

 - Hollow out x86.inline.hpp
 - Merge branch 'master' into JDK-8351162-assemblers-clean
 - Fix

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/24631/files
  - new: https://git.openjdk.org/jdk/pull/24631/files/ef531be6..73999c55

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24631&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24631&range=00-01

  Stats: 2002 lines in 48 files changed: 1717 ins; 99 del; 186 mod
  Patch: https://git.openjdk.org/jdk/pull/24631.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24631/head:pull/24631

PR: https://git.openjdk.org/jdk/pull/24631