RFR: 8355472: Clean up x86 nativeInst after 32-bit x86 removal [v2]

[Manuel Hässig]

> This PR cleans up code 32-bit x86 code in `nativeInst_x86.*` files.
> 
> Testing:
>  - [x] tier1 through tier4 on x86 plus Oracle internal testing

Manuel Hässig has updated the pull request incrementally with one additional commit since the last revision:

  Apply readability suggestion
  
  Co-authored-by: Aleksey Shipilëv <shipilev at amazon.de>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/24911/files
  - new: https://git.openjdk.org/jdk/pull/24911/files/4bbfc501..f2382dce

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24911&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24911&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/24911.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24911/head:pull/24911

PR: https://git.openjdk.org/jdk/pull/24911