RFR: 8305341: Alignment should be enforced by alignas instead of compiler specific attributes [v4]

[Julian Waters]

> C11 has been stable for a long time on all platforms, so native code can use the standard alignas operator for alignment requirements

Julian Waters has updated the pull request incrementally with four additional commits since the last revision:

 - Restore visCPP
 - Restore gcc attribute
 - Revert gcc
 - Revert

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13258/files
  - new: https://git.openjdk.org/jdk/pull/13258/files/07f5c702..e63d5938

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13258&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13258&range=02-03

  Stats: 9 lines in 3 files changed: 7 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/13258.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13258/head:pull/13258

PR: https://git.openjdk.org/jdk/pull/13258