[vectorIntrinsics] RFR: Improve mask reduction operations on AVX [v2]

[Mai Đặng Quân Anh]

> Hi,
> This patch improves the logic of vector mask reduction operations on AVX, especially int, float, long, double, by using vmovmskpd and vmovmskps instructions. I also do a little refactoring to reduce duplication in toLong. The patch temporarily disables these operations on Neon, though.
> Thank you very much.

Mai Đặng Quân Anh has updated the pull request incrementally with two additional commits since the last revision:

 - fix last true
 - further improvement

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

Changes:
  - all: https://git.openjdk.java.net/panama-vector/pull/158/files
  - new: https://git.openjdk.java.net/panama-vector/pull/158/files/1c36104b..4d0e7936

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=158&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=158&range=00-01

  Stats: 48 lines in 3 files changed: 14 ins; 8 del; 26 mod
  Patch: https://git.openjdk.java.net/panama-vector/pull/158.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-vector pull/158/head:pull/158

PR: https://git.openjdk.java.net/panama-vector/pull/158