[clang] [clang][RISCV] Enable RVV with function attribute __attribute__((target("arch=+v"))) (PR #83674)

[Camel Coder via cfe-commits]

camel-cdr wrote:

FYI, the example code you shown doesn't compile anymore: https://godbolt.org/z/ooTWEGejf

This feature is quite important, without it we can't compile in RVV by default in a lot of libraries, e.g. simdutf, flac, ...

https://github.com/llvm/llvm-project/pull/83674