Fixed behavior if missing library cudnn.lib

src/convolutional_kernels.cu

@@ -2,7 +2,9 @@
 #include "curand.h"
 #include "cublas_v2.h"
 
+#ifdef CUDNN
 #pragma comment(lib, "cudnn.lib")  
+#endif
 
 extern "C" {
 #include "convolutional_layer.h"

src/convolutional_layer.c

@@ -8,7 +8,9 @@
 #include <stdio.h>
 #include <time.h>
 
+#ifdef CUDNN
 #pragma comment(lib, "cudnn.lib")  
+#endif
 
 #ifdef AI2
 #include "xnor_layer.h"