link with nvcuvenc and ffmpeg libraries only if WITH_NVCUVID is enabled

modules/gpu/CMakeLists.txt

@@ -46,15 +46,15 @@ if(HAVE_CUDA)
 
   if(WITH_NVCUVID)
     set(cuda_link_libs ${cuda_link_libs} ${CUDA_CUDA_LIBRARY} ${CUDA_nvcuvid_LIBRARY})
-  endif()
 
-  if(WIN32)
-    find_cuda_helper_libs(nvcuvenc)
-    set(cuda_link_libs ${cuda_link_libs} ${CUDA_nvcuvenc_LIBRARY})
-  endif()
+    if(WIN32)
+      find_cuda_helper_libs(nvcuvenc)
+      set(cuda_link_libs ${cuda_link_libs} ${CUDA_nvcuvenc_LIBRARY})
+    endif()
 
-  if(WITH_FFMPEG)
-    set(cuda_link_libs ${cuda_link_libs} ${HIGHGUI_LIBRARIES})
+    if(WITH_FFMPEG)
+      set(cuda_link_libs ${cuda_link_libs} ${HIGHGUI_LIBRARIES})
+    endif()
   endif()
 else()
   set(lib_cuda "")