[lilliput-jdk17u:lilliput] RFR: 8310733: [Lilliput/JDK17] Enter object_iterate_impl() RESOLVE path only when +UCOH

[Roman Kennke]

In HeapRegion::object_iterate_impl() we currently enter the RESOLVE path when doing full-GC, regardless if it's +UCOH or -UCOH. We should only enter RESOLVE path with +UCOH.

Testing:
 - [ ] hotspot_gc -UCOH
 - [ ] hotspot_gc +UCOH

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Commit messages:
 - Improve asserts
 - 8310733: [Lilliput/JDK17] Enter object_iterate_impl() RESOLVE path only when +UCOH

Changes: https://git.openjdk.org/lilliput-jdk17u/pull/46/files
 Webrev: https://webrevs.openjdk.org/?repo=lilliput-jdk17u&pr=46&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310733
  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/lilliput-jdk17u/pull/46.diff
  Fetch: git fetch https://git.openjdk.org/lilliput-jdk17u.git pull/46/head:pull/46

PR: https://git.openjdk.org/lilliput-jdk17u/pull/46