fixed InceptionV3 dygraph class creation is not wrapped with fluid.dygraph.guard()

ppgan/metric/compute_fid.py

@@ -250,7 +250,8 @@ def calculate_fid_given_paths(paths,
         if not os.path.exists(p):
             raise RuntimeError('Invalid path: %s' % p)
 
-    if model is None:
+    if model is None and style != 'stargan':
+        with fluid.dygraph.guard():
             block_idx = InceptionV3.BLOCK_INDEX_BY_DIM[dims]
             model = InceptionV3([block_idx], class_dim=1008)