How to build a package with OpenMP support

[Mayuresh <mayuresh%acm.org@localhost>]

Trying to build wip/py-torch.

Have made a build dependency on parallel/openmp

Further, what settings are needed to get this working.

The error message is:

    -- Could NOT find OpenMP_CXX (missing: OpenMP_pthread_LIBRARY OpenMP_pthread_LIBRARY)
    -- Could NOT find OpenMP (missing: OpenMP_C_FOUND OpenMP_CXX_FOUND) CMake Error at
    third_party/ideep/mkl-dnn/third_party/oneDNN/cmake/OpenMP.cmake:118
    (message):
    OpenMP library could not be found.  Proceeding might lead to highly sub-optimal performance.
    Call Stack (most recent call first):
    third_party/ideep/mkl-dnn/third_party/oneDNN/CMakeLists.txt:117 (include)

This is a deep learning package that uses OpenMP for parallelization and
it would be indeed of little use if built without parallelism.

-- 
Mayuresh