RFR: 8296975: RISC-V: Enable UseRVA20U64 profile by default [v2]

[Xiaolin Zheng]

> The main purpose is to turn the option `UseRVC` on by default before JDK20 RDP 1. As per discussions [1], we can enable `UseRVA20U64`[2] by default to fulfill this.
> 
> 
>> build/linux-riscv64-server-fastdebug/images/jdk/bin/java -XX:+PrintFlagsFinal -version | grep -E "UseRVC|UseRVA20U64"
>      bool UseRVA20U64                              = true                                 {ARCH product} {default}
>      bool UseRVC                                   = true                                 {ARCH product} {default}
> openjdk version "20-internal" 2023-03-21
> OpenJDK Runtime Environment (fastdebug build 20-internal-adhoc..jdk)
> OpenJDK 64-Bit Server VM (fastdebug build 20-internal-adhoc..jdk, mixed mode)
> 
> 
> [1] https://mail.openjdk.org/pipermail/riscv-port-dev/2022-November/000668.html
> [2] https://github.com/openjdk/jdk/blob/873eccde01895de06e2216f6838d52d07188addd/src/hotspot/cpu/riscv/vm_version_riscv.cpp#L39-L44
> 
> Thanks,
> Xiaolin

Xiaolin Zheng has updated the pull request incrementally with one additional commit since the last revision:

  Turn off the default true UseRVA20U64 when hardware does not support C

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/11155/files
  - new: https://git.openjdk.org/jdk/pull/11155/files/9556bed6..55e3dbe7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11155&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11155&range=00-01

  Stats: 5 lines in 1 file changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11155.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11155/head:pull/11155

PR: https://git.openjdk.org/jdk/pull/11155