[riscv-port] RFR: 8283364: riscv: Intrinsify countPositives [v2]

[Feilong Jiang]

> [JDK-8281146](https://bugs.openjdk.java.net/browse/JDK-8281146) replaces `StringCoding.hasNegatives` with `countPositives` and introduces `Op_CountPositives`, which can be intrinsified on riscv port.
> 
> New added test test/hotspot/jtreg/compiler/intrinsics/string/TestCountPositives.java passed on QEMU with RVV enabled.

Feilong Jiang has updated the pull request incrementally with one additional commit since the last revision:

  instruct definition adjustment

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

Changes:
  - all: https://git.openjdk.java.net/riscv-port/pull/67/files
  - new: https://git.openjdk.java.net/riscv-port/pull/67/files/8cd6db6c..3804cf5d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=riscv-port&pr=67&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=riscv-port&pr=67&range=00-01

  Stats: 5 lines in 1 file changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/riscv-port/pull/67.diff
  Fetch: git fetch https://git.openjdk.java.net/riscv-port pull/67/head:pull/67

PR: https://git.openjdk.java.net/riscv-port/pull/67