[jdk11u-dev] RFR: 8223137: Rename predicate 'do_unroll_only()' to 'is_unroll_only()'.

[Goetz Lindenmaier]

I downport this for parity with 11.0.13-oracle.

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Commit messages:
 - Backport fcbca8224766a41659774acff0145dc1aee7d52f

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/442/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=442&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8223137
  Stats: 14 lines in 5 files changed: 3 ins; 0 del; 11 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/442.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/442/head:pull/442

PR: https://git.openjdk.java.net/jdk11u-dev/pull/442