TBB instead of OpenMP

[alecjacobson]

I'd like to integrate nasoq into a larger piece of code that is using TBB for multithreading. I'm thinking of forking nasoq and replacing all openmp parallelism with TBB.

I'm nervous to stray to far from the official nasoq branch. The easiest solution would be if the official branch would consider merging this OpenMP with TBB replacement. Is there a special reason to use OpenMP instead of TBB?

Alternatively, it might be possible to abstract the code to take either openmp or tbb (e.g., via compiler flags).

[cheshmi]

I removed OpenMP dependency for now by defining a new definition OPENMP. It is on branch https://github.com/sympiler/nasoq/tree/openmp_rem . I will merge it after I tested thoroughly.
No, there is no specific reason that I do not use TBB in NASOQ. Adding it as an option should be useful.

[cheshmi]

Merged with the main branch.