OMP and OMPI use OpenMP locks incorrectly

In sion_paropen_omp and sion_paropen_ompi, user defined locks based on OpenMP's omp_lock_t are registered via sion_lock_register_lock_callbacks. The lock instance is initialized in a global variable and while the access is "protected" against data races by a master construct, no effort is made to protect against repeated initialization. (And also omp_destroy_lock is never called.) As a consequence, any program that calls paropen_omp or paropen_ompi more than once does not conform to the OpenMP specification.