[RFC] LLVM-Libc Internal SCUDO Allocator and Allocation Model

LLVM-Libc Internal SCUDO Allocator and Allocation Model LLVM libc does not currently provide a built-in allocator implementation, even though malloc is used throughout the library. Currently, we effectively build a thin set of allocation routines on top of ::malloc and ::free, relying on either users to opt in to linking against a Scudo allocator configured with our external symbols, or overlay mode to pull in the system library and satisfy the missing symbols. For hermetic testing, we go furth...