platform independent timing in C

[jangorecki]

Timing C code is a platform independent way is a tricky process. If we could incorporate some helper function for that, then we would be able to collect more detailed timings, including timings from parallel regions. Those could be reported back to user, if verbose was used, giving some more detailed insight.

[st-pasha]

would omp_get_wtime() help?

[jangorecki]

Thanks @st-pasha, applied in #3341.