Fix bug in computing output size of IdentityOffsetProjection

Author: Peng Li

python/paddle/trainer/config_parser.py

@@ -559,6 +559,9 @@ def __init__(self, input_layer_name, offset, **xargs):
                                                        **xargs)
         self.proj_conf.offset = offset
 
+    def calc_output_size(self, input_layer_config):
+        return 0  # depends on the outside MixedLayer
+
     def calc_parameter_size(self, input_size, output_size):
         return 0