Let openblas_get_num_threads return the number of active threads
Let openblas_get_num_threads return the number of active threads

... not the number of allocated threads.

Close #760

kortschak/OpenBLAS,kortschak/OpenBLAS,kortschak/OpenBLAS,grisuthedragon/OpenBLAS,buffer51/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,buffer51/OpenBLAS,xianyi/OpenBLAS,grisuthedragon/OpenBLAS,buffer51/OpenBLAS,grisuthedragon/OpenBLAS,kortschak/OpenBLAS,kortschak/OpenBLAS,xianyi/OpenBLAS,buffer51/OpenBLAS,xianyi/OpenBLAS,buffer51/OpenBLAS,xianyi/OpenBLAS,kortschak/OpenBLAS,buffer51/OpenBLAS,xianyi/OpenBLAS,grisuthedragon/OpenBLAS,buffer51/OpenBLAS,buffer51/OpenBLAS,grisuthedragon/OpenBLAS,kortschak/OpenBLAS,grisuthedragon/OpenBLAS,grisuthedragon/OpenBLAS,xianyi/OpenBLAS,kortschak/OpenBLAS,kortschak/OpenBLAS,grisuthedragon/OpenBLAS