[lworld] RFR: 8250877: [lworld] Remove special acmp handling for isSubstitutable0 method in the JIT

[Tobias Hartmann]

The isSubstitutable0 Java method called by the VM to perform a substitutability test does not perform == on its
arguments. Special casing can be removed from the JIT.

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

Commit messages:
 - 8250877: [lworld] Remove special acmp handling for isSubstitutable0 method in the JIT

Changes: https://git.openjdk.java.net/valhalla/pull/126/files
 Webrev: https://webrevs.openjdk.java.net/valhalla/126/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8250877
  Stats: 11 lines in 2 files changed: 1 ins; 8 del; 2 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/126.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/126/head:pull/126

PR: https://git.openjdk.java.net/valhalla/pull/126