Re-instate the chroot by default code.

Index: darkstat.c
--- darkstat.c.orig
+++ darkstat.c
@@ -134,16 +134,44 @@ const char *opt_privdrop_user = NULL;
 static void cb_user(const char *arg) { opt_privdrop_user = arg; }
 
 const char *opt_daylog_fn = NULL;
-static void cb_daylog(const char *arg) { opt_daylog_fn = arg; }
+static void cb_daylog(const char *arg)
+{
+   if (opt_chroot_dir == NULL)
+      errx(1, "the daylog file is relative to the chroot.\n"
+      "You must specify a --chroot dir before you can use --daylog.");
+   else
+      opt_daylog_fn = arg;
+}
 
 const char *import_fn = NULL;
-static void cb_import(const char *arg) { import_fn = arg; }
+static void cb_import(const char *arg)
+{
+   if (opt_chroot_dir == NULL)
+      errx(1, "the import file is relative to the chroot.\n"
+      "You must specify a --chroot dir before you can use --import.");
+   else
+      import_fn = arg;
+}
 
 const char *export_fn = NULL;
-static void cb_export(const char *arg) { export_fn = arg; }
+static void cb_export(const char *arg)
+{
+   if ((opt_chroot_dir == NULL) && (opt_capfile == NULL))
+      errx(1, "the export file is relative to the chroot.\n"
+      "You must specify a --chroot dir before you can use --export.");
+   else
+      export_fn = arg;
+}
 
 static const char *pid_fn = NULL;
-static void cb_pidfile(const char *arg) { pid_fn = arg; }
+static void cb_pidfile(const char *arg)
+{
+   if (opt_chroot_dir == NULL)
+      errx(1, "the pidfile is relative to the chroot.\n"
+      "You must specify a --chroot dir before you can use --pidfile.");
+   else
+      pid_fn = arg;
+}
 
 unsigned int opt_hosts_max = 1000;
 static void cb_hosts_max(const char *arg)
@@ -306,7 +334,9 @@ static void parse_cmdline(const int argc, char * const
    if (opt_want_syslog)
       openlog("darkstat", LOG_NDELAY | LOG_PID, LOG_DAEMON);
 
-   /* default value */
+   /* some default values */
+   if (opt_chroot_dir == NULL)
+      opt_chroot_dir = CHROOT_DIR;
    if (opt_privdrop_user == NULL)
       opt_privdrop_user = PRIVDROP_USER;