[foreign-memaccess+abi] RFR: Add `final` to AbstractMemorySegmentImpl::reinterpret

[Maurizio Cimadamore]

This patch fixes an issue introduced in a recent API change [1], which causes a failure in a caller sensitive method sanity test (e.g. all caller sensitive methods must be `final`).

[1] - https://git.openjdk.org/panama-foreign/pull/797

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

Commit messages:
 - Add `final` to AbstractMemorySegmentImpl::reinterpret

Changes: https://git.openjdk.org/panama-foreign/pull/802/files
 Webrev: https://webrevs.openjdk.org/?repo=panama-foreign&pr=802&range=00
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/802.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign pull/802/head:pull/802

PR: https://git.openjdk.org/panama-foreign/pull/802