RFR: 8297912: HotSpot Style Guide should permit alignas (Second Proposal Attempt) [v2]

[Julian Waters]

> [8252584](https://bugs.openjdk.org/browse/JDK-8252584) was integrated too early due to a mistake on my part, we should redo it and go through the proper approval process this time
> 
> (The changes in this commit are exactly identical to 8252584)

Julian Waters has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'openjdk:master' into style
 - HotSpot Style Guide

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/11446/files
  - new: https://git.openjdk.org/jdk/pull/11446/files/2fb10863..792b96a2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11446&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11446&range=00-01

  Stats: 20419 lines in 319 files changed: 5751 ins; 13672 del; 996 mod
  Patch: https://git.openjdk.org/jdk/pull/11446.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11446/head:pull/11446

PR: https://git.openjdk.org/jdk/pull/11446