*: fix more initialisers (for BSD)

FreeBSD and NetBSD spew a few more warnings about variable initialisers.
Found with OSR's/NetDEF's fancy new CI system.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/zebra/ioctl.c b/zebra/ioctl.c
index d783b0a..f7a7ff4 100644
--- a/zebra/ioctl.c
+++ b/zebra/ioctl.c
@@ -52,7 +52,7 @@
 {
   int sock;
   int ret;
-  int err;
+  int err = 0;
 
   if (zserv_privs.change(ZPRIVS_RAISE))
     zlog (NULL, LOG_ERR, "Can't raise privileges");
@@ -85,7 +85,7 @@
 {
   int sock;
   int ret;
-  int err;
+  int err = 0;
 
   if (zserv_privs.change(ZPRIVS_RAISE))
     zlog (NULL, LOG_ERR, "Can't raise privileges");