[$] Comparing GCC and Clang security features

Hardening must be performed at all levels of a system, including in thecompiler that is used to build that system. There are two viable compilersin the free-software community now, each of which offers a different set ofsecurity features. Kees Cook ran a session during the Toolchainsmicroconference at the 2019 LinuxPlumbers Conference that examined the security-feature support providedby both GCC and LLVM Clang, noting the places where each one could stand toimprove.