add cudnn 5 support; test=develop

paddle/fluid/operators/cudnn_lstm_op.cu.cc

@@ -177,11 +177,20 @@ struct CudnnRNNCache {
         seed_));
 
     CUDNN_ENFORCE(platform::dynload::cudnnCreateRNNDescriptor(&rnn_desc_));
+
+#if CUDNN_VERSION >= 6000
     CUDNN_ENFORCE(platform::dynload::cudnnSetRNNDescriptor_v6(
         handle, rnn_desc_, hidden_size_, num_layers_, dropout_desc_,
         CUDNN_LINEAR_INPUT,
         is_bidirec_ ? CUDNN_BIDIRECTIONAL : CUDNN_UNIDIRECTIONAL, CUDNN_LSTM,
         CUDNN_RNN_ALGO_STANDARD, CUDNN_DATA_FLOAT));
+#else
+    CUDNN_ENFORCE(platform::dynload::cudnnSetRNNDescriptor(
+        rnn_desc_, hidden_size_, num_layers_, dropout_desc_,
+        CUDNN_LINEAR_INPUT,
+        is_bidirec_ ? CUDNN_BIDIRECTIONAL : CUDNN_UNIDIRECTIONAL, CUDNN_LSTM,
+        CUDNN_DATA_FLOAT));
+#endif
 
     CUDNN_ENFORCE(platform::dynload::cudnnCreateFilterDescriptor(&w_desc_));
     CUDNN_ENFORCE(platform::dynload::cudnnCreateFilterDescriptor(&dw_desc_));

paddle/fluid/platform/dynload/cudnn.h

@@ -125,8 +125,7 @@ extern void EnforceCUDNNLoaded(const char* fn_name);
   __macro(cudnnRNNBackwardWeights);                       \
   __macro(cudnnRNNForwardInference);                      \
   __macro(cudnnDestroyDropoutDescriptor);                 \
-  __macro(cudnnDestroyRNNDescriptor);                     \
-  __macro(cudnnSetRNNDescriptor_v6);
+  __macro(cudnnDestroyRNNDescriptor);                   
 
 CUDNN_DNN_ROUTINE_EACH(DECLARE_DYNAMIC_LOAD_CUDNN_WRAP)
 
@@ -165,6 +164,13 @@ CUDNN_DNN_ROUTINE_EACH_AFTER_R4(DECLARE_DYNAMIC_LOAD_CUDNN_WRAP)
 CUDNN_DNN_ROUTINE_EACH_R5(DECLARE_DYNAMIC_LOAD_CUDNN_WRAP)
 #endif
 
+// APIs in R6
+#if CUDNN_VERSION >= 6000
+#define CUDNN_DNN_ROUTINE_EACH_R6(__macro)  \
+  __macro(cudnnSetRNNDescriptor_v6);
+CUDNN_DNN_ROUTINE_EACH_R6(DECLARE_DYNAMIC_LOAD_CUDNN_WRAP)
+#endif
+
 #if CUDNN_VERSION >= 7001
 #define CUDNN_DNN_ROUTINE_EACH_R7(__macro)        \
   __macro(cudnnSetConvolutionGroupCount);         \