Fix having gpuarray as the default compute backend not working due to removed optimization tags.

theano/sandbox/gpuarray/__init__.py

@@ -35,7 +35,6 @@ if pygpu:
             import theano.compile
             theano.compile.shared_constructor(gpuarray_shared_constructor)
             optdb.add_tags('gpuarray_opt', 'fast_run', 'inplace')
-            optdb.add_tags('gpuarray_after_fusion', 'fast_run', 'inplace')
         elif config.gpuarray.init_device != '':
             init_dev(config.gpuarray.init_device)
         else: