RFR: 8276314: [JVMCI] check alignment of call displacement during code installation [v2]

[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.

Doug Simon has updated the pull request incrementally with one additional commit since the last revision:

  consolidated verify_aligned with is_displacement_aligned
  enhanced error message for invalid _next_call_type value
  removed os::is_MP test

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6218/files
  - new: https://git.openjdk.java.net/jdk/pull/6218/files/e1479108..b21dc4eb

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6218&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6218&range=00-01

  Stats: 9 lines in 3 files changed: 1 ins; 3 del; 5 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