Exercise the library functions with calloc returning NULL for a size
of 0. Make this a separate job with UBSan (and ASan) to detect
places where we try to dereference the result of calloc(0) or to do
things like
buf = calloc(size, 1);
if (buf == NULL && size != 0) return INSUFFICIENT_MEMORY;
memcpy(buf, source, size);
which has undefined behavior when buf is NULL at the memcpy call even
if size is 0.
This is needed because other test components jobs either use the system
malloc which returns non-NULL on Linux and FreeBSD, or the
memory_buffer_alloc malloc which returns NULL but does not give as
useful feedback with ASan (because the whole heap is a single C
object).
