[jdk11u-dev] RFR: 8273277: C2: Move conditional negation into rc_predicate

[Goetz Lindenmaier]

I backport this for parity with 11.0.15-oracle.

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Commit messages:
 - Backport 710f496456d642c3e98d230270598f0b2dc75aba

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/792/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=792&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273277
  Stats: 96 lines in 5 files changed: 71 ins; 12 del; 13 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/792.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/792/head:pull/792

PR: https://git.openjdk.java.net/jdk11u-dev/pull/792