[libc++] Add checks for misused hardening macros (#150669)
Libc++ hardening went through several iterations, sometimes within a
single release. However, some folks in the wild have picked up these
macros that were either public at some point or that were used
temporarily on `main`, and unfortunately those are now ignored.
This can lead to some users thinking they enable hardening when in
reality they don't, which is a pretty big deal. This patch simply checks
various old hardening-related macros and ensures that they are not set,
which will catch such misuse.
