RFR: 8368724: RISC-V: Remove AvoidUnalignedAccesses Flag [v8]

[Anjian Wen]

> According to the discuss in https://github.com/openjdk/jdk/pull/27445#, we can use UseUnalignedAccesses and !UseUnalignedAccesses to cover the AvoidUnalignedAccesses Flag, so I Remove the AvoidUnalignedAccesses Flag in this patch

Anjian Wen has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:

 - Merge branch 'openjdk:master' into add_unaligned_access_check
 - move the use of UseUnalignedAccesses flag after it properly assigned.
 - modify the global flag change
 - fix the use of unaligned_access
 - delete whitespace
 - Merge branch 'master' into add_unaligned_access_check
 - delete AvoidUnalignedAccesses and extra unnecessary check
 - RISC-V: Add unaligned access check

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Changes: https://git.openjdk.org/jdk/pull/27510/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27510&range=07
  Stats: 41 lines in 5 files changed: 2 ins; 9 del; 30 mod
  Patch: https://git.openjdk.org/jdk/pull/27510.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27510/head:pull/27510

PR: https://git.openjdk.org/jdk/pull/27510