Modified CUDNN headers throughout nGraph: cudnn_v7.h -> cudnn.h. (#879)

This better supports non-ubuntu/debian systems.

src/ngraph/runtime/gpu/cudnn_emitter.hpp

@@ -22,7 +22,7 @@
 #include <cublas_v2.h>
 #include <cuda.h>
 #include <cuda_runtime.h>
-#include <cudnn_v7.h>
+#include <cudnn.h>
 
 #include "ngraph/axis_set.hpp"
 #include "ngraph/runtime/gpu/gpu_runtime_context.hpp"

src/ngraph/runtime/gpu/gpu_emitter.cpp

@@ -19,7 +19,7 @@
 #include <cublas_v2.h>
 #include <cuda.h>
 #include <cuda_runtime.h>
-#include <cudnn_v7.h>
+#include <cudnn.h>
 #include <iostream>
 #include <nvrtc.h>
 #include <string>

src/ngraph/runtime/gpu/gpu_external_function.cpp

@@ -18,7 +18,7 @@
 #include <cublas_v2.h>
 #include <cuda.h>
 #include <cuda_runtime.h>
-#include <cudnn_v7.h>
+#include <cudnn.h>
 #include <fstream>
 #include <memory>
 #include <string>
@@ -287,7 +287,7 @@ void runtime::gpu::GPU_ExternalFunction::compile()
     #include <cublas_v2.h>
     #include <cuda.h>
     #include <cuda_runtime.h>
-    #include <cudnn_v7.h>
+    #include <cudnn.h>
 
     #include "ngraph/descriptor/input.hpp"
     #include "ngraph/descriptor/layout/dense_tensor_view_layout.hpp"

src/ngraph/runtime/gpu/gpu_util.hpp

@@ -24,7 +24,7 @@
 #include <cublas_v2.h>
 #include <cuda.h>
 #include <cuda_runtime.h>
-#include <cudnn_v7.h>
+#include <cudnn.h>
 #include <nvrtc.h>
 
 //why use "do...while.."