Compile bug: Riscv RVV is rv64gcv in my board

[cyk2018]

Git commit

9b17d74

Operating systems

Linux

GGML backends

CPU

Problem description & steps to reproduce

I am trying to compile llama.cpp in my riscv64 board (orangepi RV2), and I found the isa in my board is rv64gcv, but not v, so when I try to compile with cmake, the CMakeLists.txt is like xxx_v_xxx, there is '' between v and others, So the compile process will fail with an error like _v instruction is not supported.
Besides, I don't know the difference between _v and v, and in my view, is it better for we detect the isa of os and fix how we generate the string in ggml/src/ggml-cpu/CMakeLists.txt.

First Bad Commit

No response

Compile command

cmake -B build -DGGML_RVV=ON -DGGML_RV_ZICBOP=OFF -DCMAKE_BUILD_TYPE=Debug -DCMAKE_C_COMPILER=/usr/bin/cc -DCMAKE_CXX_COMPILER=/usr/bin/c++

Relevant log output

I loss the output, but is like "_v is not supported"