RFR: 8305056: Avoid unaligned access in emit_intX methods if not enabled [v4]

[Vladimir Kempik]

> Please review this change which attempts to eliminate unaligned memory stores generated by emit_int16/32/64 methods on some platforms.
> 
> Primary aim is risc-v platform. But I had to change some code in ppc/arm32/x86 to prevent possible perf degradation.

Vladimir Kempik has updated the pull request incrementally with one additional commit since the last revision:

  Rework the fix to use memcpy in codeBuffer.hpp

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13227/files
  - new: https://git.openjdk.org/jdk/pull/13227/files/ffa4edd3..c014a806

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13227&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13227&range=02-03

  Stats: 38 lines in 5 files changed: 7 ins; 11 del; 20 mod
  Patch: https://git.openjdk.org/jdk/pull/13227.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13227/head:pull/13227

PR: https://git.openjdk.org/jdk/pull/13227