[vectorIntrinsics] RFR: Merge panama-vector:master

[Jatin Bhateja]

- Merge panama-vector:master into vectorIntrinsics.
- Validation done using vector API JTREGs at different AVX levels.

Kindly review and approve.

Regards,
Jatin

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Commit messages:
 - Merge branch 'master' of http://github.com/openjdk/panama-vector into mainline_merge
 - 8282789: Create a regression test for the JTree usecase of JDK-4618767
 - 8282548: Create a regression test for JDK-4330998
 - 8282270: java/awt/Robot Screen Capture tests fail after 8280861
 - 8282723: Add constructors taking a cause to JSSE exceptions
 - 8282704: runtime/Thread/StopAtExit.java may leak memory
 - 8282534: Remove redundant null check in ChaCha20Cipher.engineInit
 - 8282574: Cleanup unnecessary calls to Throwable.initCause() in jdk.compiler
 - 8283352: [CDS] SharedBaseAddress.java fails on x86_32
 - 8283287: ClassLoader.c cleanups
 - ... and 228 more: https://git.openjdk.java.net/panama-vector/compare/701e6bab...2dc63253

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - vectorIntrinsics: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=183&range=00.0
 - panama-vector:master: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=183&range=00.1

Changes: https://git.openjdk.java.net/panama-vector/pull/183/files
  Stats: 34590 lines in 1147 files changed: 21959 ins; 5928 del; 6703 mod
  Patch: https://git.openjdk.java.net/panama-vector/pull/183.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-vector pull/183/head:pull/183

PR: https://git.openjdk.java.net/panama-vector/pull/183