Enable llvm address sanitizer #4426
Description
Motivation
To provide better diagnostics for memory-related issues.
Detailed context
Currently, we have a simple stack sanitizer by binary transformation, but this is a little bit fragile approach (e.g. assuming sp at globals[0], LLVM prologue, ...).
LLVM's address sanitizer is more reliable and Swift toolchain supports it on other platforms, so I think it's worth thinking about moving into it.