[jdk8u-dev] RFR: 8186787: clang-4.0 SIGSEGV in Unsafe_PutByte

[Zdenek Zambersky]

This backport fixes [failures](https://github.com/zzambers/jdk8u-dev/actions/runs/9858657012/job/27221579883) (segfaults) in following tests which appeared after [macos update](https://github.com/openjdk/jdk8u-dev/pull/544):

sun/misc/CopyMemory.java 
compiler/unsafe/OpaqueAccesses.java

Backport differs from original changeset, because there were significant changes/refactoring in unsafe.

**Notes:**
- original changeset changes pointer returned by `addr` (`MemoryAccess` class), to volatile. Otherwise it is basically less refactoring.
- MemoryAccess is used by `Unsafe_{Set,Put}*` and `Unsafe_{Set,Put}*Volatile` functions, defined using `DEFINE_GETSETOOP` and `DEFINE_GETSETOOP_VOLATILE` macros
- jdk8 does not have `MemoryAccess` class, so equivalent pointers, in functions mentioned higher, are cast to volatile, to achieve same effect

Testing:
Tier1: OK (fixes `sun/misc/CopyMemory.java` and `compiler/unsafe/OpaqueAccesses.java` functions on macos fixed, 1 failure on Linux x86 is timeout - seems unrelatd)

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

Commit messages:
 - Unsafe fix

Changes: https://git.openjdk.org/jdk8u-dev/pull/553/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=553&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8186787
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/553.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev.git pull/553/head:pull/553

PR: https://git.openjdk.org/jdk8u-dev/pull/553