make local_gpu_solve only work on float32

theano/sandbox/cuda/opt.py

@@ -700,6 +700,8 @@ def local_gpu_solve(node):
     CpuSolve(host_from_gpu) -> host_from_gpu(GpuSolve)
 
     """
+    if node.outputs[0].dtype != 'float32':
+        return
     if isinstance(node.op, GpuFromHost):
         host_input = node.inputs[0]
         if (host_input.owner and