Improve framework for callgrind performance unit tests

Do not abort in tests which take longer then before.
Since 4f5f6d2444a24138c3d3d378771f87cb06427195 we have nice tool to
collect callgrind results, store them..

Also, make it not necessary to duplicate anything. Any test can be turned
into a performance test by using callgrindStart/callgrindDump. You only
need to duplicate the makefile name in gb_Module_add_perfcheck_targets.

So, if the test is run as part of 'perfcheck', it runs under callgrind,
otherwise it behaves like a regular unit test.

Change-Id: I7acbb855b1823c9a32ba126abb57dccc767ca239