Note that the same limitation applies to all LLVM-based compilers

Co-authored-by: Ralf Jung <post@ralfj.de>

Author: saethlin

library/core/src/hint.rs

@@ -322,6 +322,7 @@ pub fn spin_loop() {
 ///
 /// This limitation is not specific to `black_box`; there is no mechanism in the entire Rust
 /// language that can provide the guarantees required for constant-time cryptography.
+/// (There is also no such mechanism in LLVM, so the same is true for every other LLVM-based compiler.)
 ///
 /// </div>
 ///