[jdk17u-dev] RFR: 8279695: [TESTBUG] modify compiler/loopopts/TestSkeletonPredicateNegation.java to run on C1 also

[Jonathan Dowland]

Good Morning

This pull request contains a backport of commit [86d0abb6](https://github.com/openjdk/jdk/commit/86d0abb66bd2fe1edd15b81d351ea3b3c90fd256) from the [openjdk/jdk](https://git.openjdk.java.net/jdk) repository.

The commit being backported was authored by Fairoz Matte on 11 Jan 2022 and was reviewed by Nils Eliasson.

This is a test-only change, for Oracle parity. The affected test passes for me on jdk17u-dev master before and afterwards.

Thanks!

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Commit messages:
 - Backport 86d0abb66bd2fe1edd15b81d351ea3b3c90fd256

Changes: https://git.openjdk.java.net/jdk17u-dev/pull/145/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u-dev&pr=145&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8279695
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk17u-dev/pull/145.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u-dev pull/145/head:pull/145

PR: https://git.openjdk.java.net/jdk17u-dev/pull/145