[vectorIntrinsics+mask] RFR: 8271313: AArch64: SVE backend support for masking operations with predicate feature

[Xiaohong Gong]

This is the initial SVE backend implementations for all masking operations with the SVE predicate feature. It contains:
 - SVE codegen for vector operations under a mask controlling
 - SVE codegen for vector mask operations with predicate instructions

The size of libjvm.so increases about 1.86% after adding all the backend changes. And the performance gain is about 3.7% ~ 7.88x for some masking operations of IntMaxVector with SVE 512 bits:

Benchmark                         Gain
IntMaxVector.ABSMasked            1.198
IntMaxVector.ADDMasked            1.040
IntMaxVector.ADDMaskedLanes       1.068
IntMaxVector.ANDMasked            1.117
IntMaxVector.ANDMaskedLanes       1.101
IntMaxVector.AND_NOTMasked        1.037
IntMaxVector.ASHRMasked           1.286
IntMaxVector.ASHRMaskedShift      1.096
IntMaxVector.BITWISE_BLENDMasked  1.085
IntMaxVector.LSHRMasked           1.405
IntMaxVector.LSHRMaskedShift      1.092
IntMaxVector.MAXMaskedLanes       1.079
IntMaxVector.MINMaskedLanes       1.079
IntMaxVector.MULMasked            1.370
IntMaxVector.ORMasked             1.038
IntMaxVector.ORMaskedLanes        1.103
IntMaxVector.SUBMasked            1.043
IntMaxVector.XORMasked            1.151
IntMaxVector.XORMaskedLanes       1.103
IntMaxVector.allTrue              1.157
IntMaxVector.anyTrue              1.158
IntMaxVector.gatherMasked         7.880
IntMaxVector.scatterMasked        4.732

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Commit messages:
 - 8271313: AArch64: SVE backend support for masking operations with predicate feature

Changes: https://git.openjdk.java.net/panama-vector/pull/105/files
 Webrev: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=105&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271313
  Stats: 4817 lines in 8 files changed: 3248 ins; 500 del; 1069 mod
  Patch: https://git.openjdk.java.net/panama-vector/pull/105.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-vector pull/105/head:pull/105

PR: https://git.openjdk.java.net/panama-vector/pull/105