RFR: 8255351: Add detection for Graviton 2 CPUs [v2]

[Evgeny Astigeevich]

> This commit adds detection for Graviton 1 (as Cortex-A72) and for Graviton 2 (as Neoverse N1) and enables UseSIMDForMemoryOps for them.
> 
> The patch passed jtreg tier1-2 and all gtest tests with linux-aarch64-server-release build.

Evgeny Astigeevich has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  8255351: Add detection for Graviton 2 CPUs
  
  This commit adds detection for Graviton 2 (as Neoverse N1)
  and enables UseSIMDForMemoryOps for it.

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1315/files
  - new: https://git.openjdk.java.net/jdk/pull/1315/files/204f1f68..60e28f57

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1315&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1315&range=00-01

  Stats: 7 lines in 1 file changed: 0 ins; 7 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1315.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1315/head:pull/1315

PR: https://git.openjdk.java.net/jdk/pull/1315