Leave OMP_WAIT_POLICY set to active for Mac OS X. Seems to improve performance slightly.

gprMax/input_cmds_singleuse.py

@@ -62,7 +62,8 @@ def process_singlecmds(singlecmds, G):
 
     # Number of threads (OpenMP) to use
     cmd = '#num_threads'
-    # os.environ['OMP_WAIT_POLICY'] = 'ACTIVE'  # What to do with threads when they are waiting; can drastically effect performance
+    if sys.platform = 'darwin':
+        os.environ['OMP_WAIT_POLICY'] = 'ACTIVE'  # What to do with threads when they are waiting; can drastically effect performance
     os.environ['OMP_DYNAMIC'] = 'FALSE'
     os.environ['OMP_PROC_BIND'] = 'TRUE'  # Bind threads to physical cores