vlib: add nosyslog unix option

The "nosyslog" option disables syslog just like the "interactive" mode
but can be used together with "nodaemon".

This is useful for when VPP is running under a process supervisor like
runit or daemontools that pipe the stdout/stderr to a dedicated logger
service.

Type: feature

Change-Id: Ic4287338d6836fea9f3eabdcf960dc1f51875dd1
Signed-off-by: Ruslan Babayev <ruslan@babayev.com>
diff --git a/src/vlib/unix/unix.h b/src/vlib/unix/unix.h
index e71b0ba..9fa95a0 100644
--- a/src/vlib/unix/unix.h
+++ b/src/vlib/unix/unix.h
@@ -59,6 +59,8 @@
   /* Run interactively or as daemon (background process). */
 #define UNIX_FLAG_INTERACTIVE (1 << 0)
 #define UNIX_FLAG_NODAEMON (1 << 1)
+#define UNIX_FLAG_NOSYSLOG (1 << 2)
+
 
   /* CLI listen socket. */
   clib_socket_t cli_listen_socket;