[jdk11u-dev] RFR: 8253795: Implementation of JEP 391: macOS/AArch64 Port

[Vladimir Kempik]

Initial version of JEP-391 backport to jdk11u.
Build system changes are mostly clean, except cds disabling part, it's copy&paste from aix part.
Things needing attention: os_bsd_aarch64.cpp and W^X transitions.
serviceability agent is mostly clean.
This passed GHA_tier1 testing.
Full regression testing is running now on Azul's infra, will report/update PR when done.
Sharing this PR slightly earlier to let other interested parties to run the tests too.
Example of cross-building on intel mac (needs Xcode12/13):
sh configure --with-boot-jdk=/Library/Java/JavaVirtualMachines/zulu-11.jdk/Contents/Home/ --with-build-jdk=/Library/Java/JavaVirtualMachines/zulu-11.jdk/Contents/Home/ --disable-warnings-as-errors --openjdk-target=aarch64-apple-darwin --with-extra-cflags='-arch arm64' --with-extra-ldflags='-arch arm64' --with-extra-cxxflags='-arch arm64'

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Commit messages:
 - Trailing white space removal
 - Fix up linux_aarch64
 - Initial commit

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/715/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=715&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8253795
  Stats: 3093 lines in 70 files changed: 2998 ins; 24 del; 71 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/715.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/715/head:pull/715

PR: https://git.openjdk.java.net/jdk11u-dev/pull/715