fix tests errors when scipy is not available.

theano/tensor/tests/test_basic.py

@@ -1245,6 +1245,8 @@ if imported_scipy_special:
 else:
     expected_erf = []
     expected_erfc = []
+    expected_gammaln = []
+    expected_psi = []
     skip_scipy = "scipy is not present"
 
 ErfTester = makeBroadcastTester(