RFR: 8276314: [JVMCI] check alignment of call displacement during code installation

[Doug Simon]

This PR add verification of code alignment invariants related to x64 call instructions during code installation.
This in turn allows a JVMCI compilation that generates a misaligned call to fail gracefully (i.e. bailout) instead of the VM crashing when it checks alignment before patching the displacement of a call instruction.

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Commit messages:
 - ensure call displacement is aligned during code installation

Changes: https://git.openjdk.java.net/jdk/pull/6218/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6218&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8276314
  Stats: 16 lines in 3 files changed: 9 ins; 1 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6218.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6218/head:pull/6218

PR: https://git.openjdk.java.net/jdk/pull/6218