Removing old memory debugging code

Hi,
  I noted that there are some residual attempt to use some memory
debugging all around. One is the manual "crumbs" in dblib tests and
the other is a lot of includes for dmalloc headers. They are quite
confusing, not used since a while and probably not that updated
(valgrind is used instead which is much easier and does not require
source changes).

If nobody complain I will remove both from sources.

Frediano