RFR: 8371643: Remove ThreadLocalAllocBuffer::_reserve_for_allocation_prefetch [v2]

[Albert Mingkun Yang]

> Trivial removing obsoleted code for unsupported arch.
> 
> Test: tier1

Albert Mingkun Yang has updated the pull request incrementally with one additional commit since the last revision:

  review

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Changes:
  - all: https://git.openjdk.org/jdk/pull/28240/files
  - new: https://git.openjdk.org/jdk/pull/28240/files/03330ac2..0e447848

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28240&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28240&range=00-01

  Stats: 9 lines in 2 files changed: 0 ins; 8 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/28240.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28240/head:pull/28240

PR: https://git.openjdk.org/jdk/pull/28240