[common.profiler] add DUNE_STUFF_DO_PROFILE
[common.profiler] add DUNE_STUFF_DO_PROFILE

This variable is intended as a library wide flag to enable profiling and
can (/should) be used to guard profiling of library code.

renemilk/DUNE-Stuff,renemilk/DUNE-Stuff,renemilk/DUNE-Stuff