RFR: 8268553: [lworld] CI must return secondary mirror when accessing CONSTANT_Class with Q-signature

[Frederic Parain]

Please review this small change in CI to return the secondary mirror when accessing a CONSTANT_Class_info entry containing a Q-signature.
This change fixes all compiler tests failures in the lqagain branch but the ones depending on intrinsics (Class::getSuperclass intrinsic and Class::isAssignableFrom intrinsics need to be fixed in a separate changeset).

Thank you,

Fred

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Commit messages:
 - Add secondary mirror support to CI

Changes: https://git.openjdk.java.net/valhalla/pull/442/files
 Webrev: https://webrevs.openjdk.java.net/?repo=valhalla&pr=442&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268553
  Stats: 14 lines in 3 files changed: 13 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/442.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/442/head:pull/442

PR: https://git.openjdk.java.net/valhalla/pull/442