Linker invoked with print-gc-sections reported a number of unused functions in libnet:

closefd
NET_Dup2
NET_SocketClose
NET_Read
NET_NonBlockingRead
NET_RecvFrom
NET_Send
NET_SendTo
NET_Accept
NET_Timeout
NET_ThrowCurrent
NET_GetFileDescriptorID

The last use of (at least some of) these functions was removed in JDK-8253119; the functions should be removed as well.