Dump core file to DESTDIR instead to PWD

When I debug remote Linux and my program fail, then Qt Creator kindly dumps memory to the "core" file (without quotes). From my point of view it is pretty useless (how ever maybe some leading hackers can use it).

In my opinion this file should be dumped to the DESTDIR (where final exe is copied after compilation).

The other possible, non intrusive destination for "core" file is OUT_PWD (where make files are generated in build dir).

I post this suggestion because when I do backup of my projects or when I add files to the git repository, then always I have to remember about "core" files.