Check if WDT_DEVNODE is defined, may not be enabled in configure

When this code was moved from finit.c we rely on WDT_DEVNODE to be
defined in config.h, which is controlled by configure.  Meaning, before
the relocation, Finit did not honor the configure settings.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/finit.c

@@ -59,7 +59,6 @@
 #include "util.h"
 #include "utmp-api.h"
 #include "schedule.h"
-#include "watchdog.h"
 
 int   runlevel  = 0;		/* Bootstrap 'S' */
 int   cfglevel  = RUNLEVEL;	/* Fallback if no configured runlevel */