[clang] [llvm] [TargetLibraryInfo] Add libmvec support for risc-v (PR #119844)

[Zhijin Zeng via llvm-commits]

zengdage wrote:

@mga-sc Hi, can you help to review the pr? I add RVVM1/2/4/8 in VFISAKind to support multiple LMUL value, maybe it can take full advantage of rvv register group. Your pr (https://github.com/llvm/llvm-project/pull/114014) looks like just support LMUL=2.

https://github.com/llvm/llvm-project/pull/119844