[jdk11u-dev] RFR: 8222825: ARM32 SIGILL issue on single core CPU (not supported PLDW instruction)

[Boris Ulasevich]

This is the request to backport the fix to jdk11u.
The change fixes SIGILL on ARM machines without the Multiprocessing Extensions and brings no risk for other platforms.

The original patch [1] has minor conflicts with os::is_MP [2] and AArch64 Port [3] removal updates.
 [1] https://github.com/openjdk/jdk/commit/989fa190
[2] https://github.com/openjdk/jdk/commit/a3cd6a1a
[3] https://github.com/openjdk/jdk/commit/05027c12

The jtreg tests are Ok.

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Commit messages:
 - 8222825: ARM32 SIGILL issue on single core CPU (not supported PLDW instruction)

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/652/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=652&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8222825
  Stats: 39 lines in 5 files changed: 33 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/652.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/652/head:pull/652

PR: https://git.openjdk.java.net/jdk11u-dev/pull/652