[jdk17u-dev] RFR: 8305056: Avoid unaligned access in emit_intX methods if it's unsupported

[Vladimir Kempik]

Please review this backport to jdk17u-dev, it doesn't apply clean due to different codestyle of emit_int32 in jdk17u-dev (linebreaks)

this is important for risc-v port as there support for misaligned memory access is implementation specific option.
This commit changes logic from "always misaligned stores on all architectures" to "compiler (gcc/clang) knows better for every architecture"

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Commit messages:
 - 8305056: Avoid unaligned access in emit_intX methods if it's unsupported

Changes: https://git.openjdk.org/jdk17u-dev/pull/1638/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1638&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305056
  Stats: 15 lines in 1 file changed: 8 ins; 1 del; 6 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1638.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1638/head:pull/1638

PR: https://git.openjdk.org/jdk17u-dev/pull/1638