handle nan in run.py test=develop (#2240)

mobile/tools/python/fluidtools/run.py

@@ -559,7 +559,7 @@ def check_mobile_results(args, fuse, mem_opt):
                     for i in range(len(values1)):
                         v1 = values1[i]
                         v2 = values2[len(shape) + i]
-                        if abs(v1 - v2) > diff_threshold:
+                        if ((not math.isnan(v1)) and math.isnan(v2)) or abs(v1 - v2) > diff_threshold:
                             error_index = index
                             break
                 checked_names.append(op_output_var_name)