RFR: 8374712: AOTMappedHeapWriter::relocate_field_in_buffer should use CompressedOops::narrow_oop_cast

[Kim Barrett]

Please review this change to use CompressedOops::narrow_oop_cast instead of
potentially UB checked_cast to convert an integer to a narrowOop.
narrow_oop_cast does not have the UB problem.

Testing: mach5 tier1

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Commit messages:
 - use narrow_oop_cast

Changes: https://git.openjdk.org/jdk/pull/29100/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29100&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8374712
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/29100.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29100/head:pull/29100

PR: https://git.openjdk.org/jdk/pull/29100