[clang] [llvm] [RISCV] Add riscv_atomic.h and Zawrs/Zalrsc builtins (PR #94578)

[Craig Topper via cfe-commits]

topperc wrote:

> Compilers are free to insert whatever stack spills and reloads they want in between your inline assembly blocks or intrinsic calls

Especially with -O0.

https://github.com/llvm/llvm-project/pull/94578