Updated OpenMP regression test to set the number of threads based on the OMP_NUM_THREADS environment variable.
Updated OpenMP regression test to set the number of threads based on the OMP_NUM_THREADS environment variable.

liuqx315/Sundials,liuqx315/Sundials,liuqx315/Sundials,liuqx315/Sundials,liuqx315/Sundials,liuqx315/Sundials