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

[Roger Ferrer Ibáñez via llvm-commits]

rofirrim wrote:

> Just FYI, we have implemented `__clear_cache` via calling `__NR_riscv_flush_icache` in `compiler-rt`:

Thanks for the update. Do you use `compiler-rt` even on glibc targets? Not sure if there is a way to know we're on a glibc target **and** we are using `libgcc`  for the compiler runtime (which would indeed have to call `__riscv_flush_icache`).

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