RFR: 8351152: x86: Remove code blocks that handle UseSSE < 2

[Aleksey Shipilev]

32-bit x86 was the platform that supported `UseSSE < 2`. 64-bit x86 baselines on `UseSSE >= 2`. After 32-bit x86 code is gone, we can remove all code blocks that are there to support `UseSSE < 2`.

Additional testing:
 - [x] Linux x86_64 server fastdebug, `all`

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Commit messages:
 - Also 24-bit removals
 - Touchups
 - Fix

Changes: https://git.openjdk.org/jdk/pull/24484/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24484&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351152
  Stats: 643 lines in 16 files changed: 34 ins; 363 del; 246 mod
  Patch: https://git.openjdk.org/jdk/pull/24484.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24484/head:pull/24484

PR: https://git.openjdk.org/jdk/pull/24484