Presently, RIOT just emits a warning when a stack overflow is
encountered but still resumes execution. In my view, execution should be
aborted as the detection of a stack overflows via the heuristic provided
by the scheduler is an unrecoverable error.
I ran into this while performing automated tests of a RIOT application
where a stack overflow occurred but I only noticed this after inspecting
the application output more closely.
Similar to SSP failures, I added crash_code for stack overflows.
Use `uintptr_t` for arithmetic rather than `const char *` to fix the
following warning:
> comparePointers: Subtracting pointers that point to different objects
