[jdk18] RFR: 8278489: Preserve result in native wrapper with +UseHeavyMonitors

[Roman Kennke]

Testing observed a few failures after JDK-8276901. The reason for the failures is in the native-wrappers, in the +UseHeavyMonitors paths, we don't preserve the result register after the native call.

Testing:
 - [x] java/awt/color, sun/java2d/cmm tests (x86_32, x86_64 x -UseHeavyMonitors, +UseHeavyMonitors)
 - [ ] tier1 (x86_32, x86_64 x -UseHeavyMonitors, +UseHeavyMonitors)

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Commit messages:
 - 8278489: Preserve result in native wrapper with +UseHeavyMonitors

Changes: https://git.openjdk.java.net/jdk18/pull/16/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk18&pr=16&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278489
  Stats: 12 lines in 2 files changed: 4 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk18/pull/16.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18 pull/16/head:pull/16

PR: https://git.openjdk.java.net/jdk18/pull/16