We must include gettext.h before missing.h as it includes system

headers.  Also add missing DEFAULT_TEXT_DOMAIN defines in sudoers
audit code that does not include sudoers.h.

src/net_ifs.c

@@ -84,15 +84,15 @@ struct rtentry;
 # include <ifaddrs.h>
 #endif
 
+#define DEFAULT_TEXT_DOMAIN	"sudo"
+#include "gettext.h"		/* must be included before missing.h */
+
 #include "missing.h"
 #include "alloc.h"
 #include "fatal.h"
 #include "sudo_conf.h"
 #include "sudo_debug.h"
 
-#define DEFAULT_TEXT_DOMAIN	"sudo"
-#include "gettext.h"
-
 /* Minix apparently lacks IFF_LOOPBACK */
 #ifndef IFF_LOOPBACK
 # define IFF_LOOPBACK	0