RFR: 8323552: AbstractMemorySegmentImpl#mismatch returns -1 when comparing distinct areas of the same instance of MemorySegment

[Peter Levart]

I belive there is a bug in `AbstractMemorySegmentImpl#mismatch` method. It returns `-1` (meaning that regions are equal) when passing the same instance of MemorySegment as both `srcSegment` and `dstSegment` parameters regardless of whether `srcFromOffset` and `dstFromOffset` as well as `srcToOffset` and `dstToOffset` are also equal.

Am I right?

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Commit messages:
 - fix mismatch avoidance of memory comparison

Changes: https://git.openjdk.org/jdk/pull/17354/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17354&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8323552
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/17354.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17354/head:pull/17354

PR: https://git.openjdk.org/jdk/pull/17354