Fix error messages.

theano/sandbox/gpuarray/dnn_pool_grad.c

@@ -106,7 +106,7 @@ int APPLY_SPECIFIC(dnn_pool_grad)(PyGpuArrayObject *inp,
       beta = (void *)&betaf;
       break;
     default:
-      PyErr_SetString(PyExc_TypeError, "Unsupported type in pooling");
+      PyErr_SetString(PyExc_TypeError, "Unsupported type in pooling gradient");
       return 1;
     }
 

theano/sandbox/gpuarray/dnn_softmax.c

@@ -67,7 +67,7 @@ int APPLY_SPECIFIC(softmax)(PyGpuArrayObject *x,
       beta = (void *)&betaf;
       break;
     default:
-      PyErr_SetString(PyExc_TypeError, "Unsupported type in pooling");
+      PyErr_SetString(PyExc_TypeError, "Unsupported type in softmax");
       return 1;
     }
 

theano/sandbox/gpuarray/dnn_softmax_grad.c

@@ -80,7 +80,7 @@ int APPLY_SPECIFIC(softmax_grad)(PyGpuArrayObject *dy,
       beta = (void *)&betaf;
       break;
     default:
-      PyErr_SetString(PyExc_TypeError, "Unsupported type in pooling");
+      PyErr_SetString(PyExc_TypeError, "Unsupported type in softmax gradient");
       return 1;
     }