compile cuda_ndarray.cu with -O3 flags.

theano/sandbox/cuda/__init__.py

@@ -164,7 +164,7 @@ if compile_cuda_ndarray and cuda_available:
                             code,
                             location=cuda_ndarray_loc,
                             include_dirs=[cuda_path], libs=['cublas'],
-                            preargs=compiler.compile_args())
+                            preargs=['-O3'] + compiler.compile_args())
                     from cuda_ndarray.cuda_ndarray import *
             except Exception, e:
                 _logger.error("Failed to compile cuda_ndarray.cu: %s", str(e))