RFR: 8255886: Shenandoah: Avoid register clash when calling LRB-runtime from interpreter [v5]

[Roman Kennke]

> JDK-8255762 caused test failure on Windows because of overlapping argument registers in the LRB runtime call. The problem is more general, though, but hasn't manifested anywhere else.
> 
> Testing: hotspot_gc_shenandoah (linux: x86_64, x86_32, windows: x86_64)

Roman Kennke has updated the pull request incrementally with one additional commit since the last revision:

  Some touch-ups

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1054/files
  - new: https://git.openjdk.java.net/jdk/pull/1054/files/e83cae28..607b98f7

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1054&range=04
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1054&range=03-04

  Stats: 8 lines in 1 file changed: 5 ins; 2 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1054.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1054/head:pull/1054

PR: https://git.openjdk.java.net/jdk/pull/1054