RFR: 8354231: x86: Purge FPU support from (Macro)Assembler after 32-bit x86 removal

[Aleksey Shipilev]

There are lots of cleanups possible in (Macro)Assembler after 32-bit x86 removal. This cleanup is focused on removing the large parts of x87 FPU support that are no longer needed. Note that _some_ math stubs are actually using x87 FPU in a very limited manner, but the implementations use separate definitions (under `LP64`). Those are left alone, and we clean up x86_32 code here.

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

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/24558/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24558&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8354231
  Stats: 819 lines in 7 files changed: 0 ins; 817 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/24558.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24558/head:pull/24558

PR: https://git.openjdk.org/jdk/pull/24558