Make cuda backend expose GpuAllocEmpty op

theano/sandbox/cuda/__init__.py

@@ -316,7 +316,7 @@ if cuda_available:
             GpuDimShuffle, GpuCAReduce, GpuReshape, GpuContiguous,
             GpuSubtensor, GpuIncSubtensor,
             GpuAdvancedSubtensor1, GpuAdvancedIncSubtensor1,
-            GpuFlatten, GpuShape, GpuAlloc, GpuSplit,
+            GpuFlatten, GpuShape, GpuAlloc, GpuAllocEmpty, GpuSplit,
             GpuJoin, fscalar, fvector, fmatrix, frow, fcol,
             ftensor3, ftensor4,
             scalar, vector, matrix, row, col,