ad552bc17e
This change is needed for compiler-builtins to check for this feature when implementing memcpy/memset. See: https://github.com/rust-lang/compiler-builtins/pull/365 The change just does compile-time detection. I think that runtime detection will have to come in a follow-up CL to std-detect. Like all the CPU feature flags, this just references #44839 Signed-off-by: Joe Richey <joerichey@google.com>