LibCore: Remove CSocket's bind() and listen().

We're going to be using dedicated server socket classes instead.
This was only implemented for CLocalSocket, and clients have been switched
over to using CLocalServer.

Libraries/LibCore/CSocket.cpp

@@ -131,13 +131,6 @@ bool CSocket::send(const ByteBuffer& data)
     return true;
 }
 
-bool CSocket::listen()
-{
-    int rc = ::listen(fd(), 5);
-    set_error(errno);
-    return rc == 0;
-}
-
 void CSocket::did_update_fd(int fd)
 {
     if (fd < 0) {