Unify tracing infrastructure

[rschoene]

In order to avoid too many ifdefs in the main code, there should be a header that maps common tracing calls to explicit ones (currently VT and Score-P, but potentially also Caliper and others). Likewise, CMake should then also not have flags for the specific tracing infrastructures, but to files that map the common tracing calls to those of VT/Score-P/Caliper ToDos:

• [ ] Create a common header for Tracing include/firestarter/measurement/FS-Tracing.h
  • [ ] This header should be in C so that it can easily be matched against other C-based libraries
  • [ ] The standard implementation in include/firestarter/measurement/FS-Tracing.h should just be some do nothing
  • [ ] If a compiler flag indicates the use of a different header, this should be included instead
  • [ ] There shall be example implementations for these "diferent headers" that map calls to this header to VT, Score-P, and maybe others placed in in examples/tracing
• [ ] Tracing examples will not be part of any testing, this should be in the README
• [ ] Replace all VT/Score-P calls with calls to his header
• [ ] Create example implementations for VT and Score-P
• [ ] Remove VT/Score-P Flags from CMake
• [ ] Add Flags to CMake:
  • [ ] for passing libraries / library pathes
  • [ ] one header (for matching the trace calls from FS and including other headers) and include pathes
  • [ ] and maybe one C file for things that cannot be done in the header

[rschoene]

Anyone who wants to participate, have a look at the unifytracing branch

[rschoene]

I opened a branch, comments are welcome