[jdk17u-dev] RFR: 8326936: RISC-V: Shenandoah GC crashes due to incorrect atomic memory operations

[Gui Cao]

The same issue reproduces for 17u and 21u too if we apply fix for JDK- 8316186 and JDK-8316893 which are both code cleanup/enhancement. So I suggest we backport JDK-8326936 and its followup fix JDK-8330242 to be safe. 

### Testing
- [x] The affected jtreg test cases all pass with jdk release built with latest gcc-13 development branch.

-------------

Commit messages:
 - Backport 8330242: RISC-V: Simplify and remove CORRECT_COMPILER_ATOMIC_SUPPORT in atomic_linux_riscv.hpp
 - Backport 8326936: RISC-V: Shenandoah GC crashes due to incorrect atomic memory operations
 - Backport 8316186: RISC-V: Remove PlatformCmpxchg<4>

Changes: https://git.openjdk.org/jdk17u-dev/pull/2417/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2417&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8326936
  Stats: 75 lines in 1 file changed: 38 ins; 33 del; 4 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2417.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2417/head:pull/2417

PR: https://git.openjdk.org/jdk17u-dev/pull/2417