RFR: 8280476: [macOS] : hotspot arm64 bug exposed by latest clang

[Daniel D.Daugherty]

A trivial fix to solve undefined behavior in src/hotspot/cpu/aarch64/immediate_aarch64.cpp:
replicate().

I was not able to reproduce the reported failure using:

  Xcode: Version 13.2.1 (13C100) which include clang Apple LLVM 13.0.0 (clang-1300.0.29.30)

so I'm moving forward with the proposed fix from a code inspection
point of view.

I've tested this fix with Mach5 Tier[1-6]. Tier1 and Tier2 have completed with
no failures. Tier[3-6] are still running.

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Commit messages:
 - 8280476: [macOS] : hotspot arm64 bug exposed by latest clang

Changes: https://git.openjdk.java.net/jdk/pull/7270/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7270&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280476
  Stats: 8 lines in 1 file changed: 7 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7270.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7270/head:pull/7270

PR: https://git.openjdk.java.net/jdk/pull/7270