[llvm] [RISCV] Lower llvm.clear_cache to __riscv_flush_icache for glibc targets (PR #93481)

[Roger Ferrer Ibáñez via llvm-commits]

rofirrim wrote:

@dyung if you can revert the change that'd be helpful, so I can investigate. Thanks!

https://github.com/llvm/llvm-project/pull/93481