Correctly check which sync to call, in case both back-end are available, use the one used.

theano/misc/check_blas.py

@@ -90,9 +90,9 @@ def execute(execute=True, verbose=True, M=2000, N=2000, K=2000,
     if execute:
         sync = (hasattr(theano, "sandbox") and
                 hasattr(theano.sandbox, "cuda") and
-                theano.sandbox.cuda.cuda_available)
+                isinstance(c, theano.sandbox.cuda.CudaNdarraySharedVariable))
         sync2 = (hasattr(theano, "gpuarray") and
-                 theano.gpuarray.pygpu_activated)
+                 isinstance(c, theano.gpuarray.GpuArraySharedVariable))
         t0 = time.time()
         for i in range(iters):
             f()