[jdk17u-dev] RFR: 8282874: Bad performance on gather/scatter API caused by different IntSpecies of indexMap

[Martin Doerr]

Clean backport of [JDK-8282874](https://bugs.openjdk.java.net/browse/JDK-8282874)

-------------

Commit messages:
 - Backport 5c408c1410e15087f735a815b7edc716d514b1b3

Changes: https://git.openjdk.java.net/jdk17u-dev/pull/314/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u-dev&pr=314&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8282874
  Stats: 42 lines in 7 files changed: 0 ins; 0 del; 42 mod
  Patch: https://git.openjdk.java.net/jdk17u-dev/pull/314.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u-dev pull/314/head:pull/314

PR: https://git.openjdk.java.net/jdk17u-dev/pull/314