fix CUDNN_VERSION for backward of CudnnBatchNormLayer (#61)

paddle/gserver/layers/CudnnBatchNormLayer.cpp

@@ -114,27 +114,30 @@ void CudnnBatchNormLayer::backward(const UpdateCallback& callback) {
   } else {
     create(tmpBiasGrad_, 1, channels_, &betaGrad);
   }
-#if CUDNN_VERSION < 5000
+
   // because of the different api of cudnn v4 and v5.
+  if (hl_get_cudnn_lib_version() < 5000) {
     if (weight_->getWGrad()) {
       create(tmpWGrad_, 1, channels_, &gammaGrad);
     }
     if (biases_ && biases_->getWGrad()) {
       create(tmpBiasGrad_, 1, channels_, &betaGrad);
     }
-#endif
+  }
+
   hl_batch_norm_backward(ioDesc_, input, ioDesc_, outGrad,
                          ioDesc_, inGrad, bnParamDesc_,
                          gamma, gammaGrad, betaGrad,
                          EPS, savedMean, savedInvVar);
 
-#if CUDNN_VERSION < 5000
   // because of the different api of cudnn v4 and v5.
+  if (hl_get_cudnn_lib_version() < 5000) {
     if (weight_->getWGrad() && biases_->getWGrad()) {
       weight_->getWGrad()->add(*tmpWGrad_);
       biases_->getWGrad()->add(*tmpBiasGrad_);
     }
-#endif
+  }
+
   {
     REGISTER_TIMER_INFO("WeightUpdate", getName().c_str());
     biases_->getParameterPtr()->incUpdate(callback);