[lworld] RFR: 8334747: [lworld] C1 needs adjustments after JDK-8294866

[Frederic Parain]

Adjustments in C1 after the addition of ACC_IDENTITY to arrays' modifiers.

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Commit messages:
 - Re-implement without branches
 - Fix getModifiers in C1 code

Changes: https://git.openjdk.org/valhalla/pull/1146/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1146&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8334747
  Stats: 48 lines in 3 files changed: 25 ins; 2 del; 21 mod
  Patch: https://git.openjdk.org/valhalla/pull/1146.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1146/head:pull/1146

PR: https://git.openjdk.org/valhalla/pull/1146