[jdk17u-dev] RFR: 8311249: Remove unused MemAllocator::obj_memory_range

[Aleksey Shipilev]

Semi-clean backport to eliminate unused method, and make life easier for downstreams like Lilliput JDK 17.

There was a contextual difference around this hunk, as mainline has `protected` moved by [JDK-8294900](https://bugs.openjdk.org/browse/JDK-8294900), which I don't want to backport.


protected:
  virtual MemRegion obj_memory_range(oop obj) const;


Additional testing:
 - [ ] GHA builds

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Depends on: https://git.openjdk.org/jdk17u-dev/pull/1534

Commit messages:
 - Backport 711cddd899048236bbc3c0aa7e4ac0fc8aebe4d2

Changes: https://git.openjdk.org/jdk17u-dev/pull/1535/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1535&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311249
  Stats: 15 lines in 2 files changed: 0 ins; 15 del; 0 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1535.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1535/head:pull/1535

PR: https://git.openjdk.org/jdk17u-dev/pull/1535