mcheck: introduce mcheck_on_ramrelocation(.)

The using of pre-reloc/malloc_simple heap is
too hard to follow after the relocation.

So lets drop it from the pedantic registry
and switch to dlmalloc, when moved.

The offset is ignored, but kept in the API
for the probable case, when that early
heap is relocated too.

Signed-off-by: Eugene Uriev <eugeneuriev@gmail.com>