[clang] [llvm] [RISCV][FMV] Support target_clones (PR #85786)

[Piyou Chen via llvm-commits]

BeMg wrote:

Support new syntax `Priority` to define priority for specific version from user. 

https://github.com/riscv-non-isa/riscv-c-api-doc/pull/85

https://github.com/llvm/llvm-project/pull/85786