Use config.dnn.enabled in gpuarray

theano/sandbox/gpuarray/dnn.py

@@ -84,6 +84,9 @@ def _dnn_check_version():
 
 
 def dnn_present():
+    if config.dnn.enabled == "False":
+        dnn_present.msg = "disabled by dnn.enabled flag"
+        dnn_present.avail = False
     if dnn_present.avail is not None:
         return dnn_present.avail
 
@@ -98,6 +101,12 @@ def dnn_present():
         if not dnn_present.avail:
             raise RuntimeError(dnn_present.msg)
 
+    if config.dnn.enabled == "True":
+        if not dnn_present.avail:
+            raise RuntimeError(
+                "You enabled CuDNN, but we aren't able to use it: %s" %
+                dnn_present.msg)
+
     return dnn_present.avail
 
 dnn_present.avail = None