top: Always exit from sig_abexit().

The default action for SIGURG is to ignore the signal, for example.
This is very similar to the patch "ps/display.c: Always exit from
signal_handler()."

top/top.c

@@ -582,6 +582,7 @@ static void sig_abexit (int sig) {
       , sig, signal_number_to_name(sig), Myname);
    signal(sig, SIG_DFL);     // allow core dumps, if applicable
    raise(sig);               // ( plus set proper return code )
+   _exit(sig | 0x80);        // if default sig action is ignore
 } // end: sig_abexit