Terminate execl() arguments with NULL instead of 0

Makes sure that a full 64-bits of 0 is passed in 64-bit builds, and
clears gcc warning of:

menus.c: In function ‘System’:
menus.c:2344:2: warning: missing sentinel in function call

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/menus.c b/src/menus.c
index eb8f0e8..4c0e22a 100644
--- a/src/menus.c
+++ b/src/menus.c
@@ -2341,7 +2341,7 @@ System (char *s)
     int pid, status;
     if ((pid = fork ()) == 0) {
 	(void) setpgrp();
-	execl ("/bin/sh", "sh", "-c", s, 0);
+	execl ("/bin/sh", "sh", "-c", s, NULL);
     } else
 	waitpid (pid, &status, 0);
     return status;