Do not setup SIGHUP signal handler if we are in the batch mode

Top enables a signal handler for the SIGHUP signal (loss of terminal).  While
this makes sense for top's default interactive mode, it doesn't make any sense
for batch mode. If you run top in nohup just to collect data over time and
disconnect top finishes which is not what one would expect.
Index: procps-3.2.8/top.c

---
 top/top.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- top/top.c
+++ top/top.c	2018-04-04 11:33:59.278280201 +0000
@@ -3691,7 +3691,13 @@ static void before (char *me) {
    sa.sa_flags = 0;
    for (i = SIGRTMAX; i; i--) {
       switch (i) {
-         case SIGALRM: case SIGHUP:  case SIGINT:
+         case SIGHUP:
+            if (Batch)
+              sa.sa_handler = SIG_IGN;
+            else
+              sa.sa_handler = sig_endpgm;
+            break;
+         case SIGALRM: case SIGINT:
          case SIGPIPE: case SIGQUIT: case SIGTERM:
          case SIGUSR1: case SIGUSR2:
             sa.sa_handler = sig_endpgm;