Move gettytab to libexec/getty/

Approved by:	re (gjb), will (mentor)
Differential Revision:	https://reviews.freebsd.org/D16953

etc/Makefile

@@ -15,7 +15,6 @@ SUBDIR+=sendmail
 BIN1=	crontab \
 	dhclient.conf \
 	disktab \
-	gettytab \
 	group \
 	hosts \
 	hosts.allow \

libexec/getty/Makefile

@@ -1,6 +1,7 @@
 #	from: @(#)Makefile	8.1 (Berkeley) 6/4/93
 # $FreeBSD$
 
+CONFS=	gettytab
 PROG=	getty
 SRCS=	main.c init.c subr.c chat.c
 LIBADD=	util