Remove <sgtty.h> now it has no practical usage.

When I turned sgtty into a binary-only interface (last month), I added
this explicit #error to the header file, to make sure nobody forgot to
remove the header file after updating world.

I think it is now a good moment to remove this header file.

Approved by:	philip (mentor)

ObsoleteFiles.inc

@@ -14,6 +14,8 @@
 # The file is partitioned: OLD_FILES first, then OLD_LIBS and OLD_DIRS last.
 #
 
+# 20080725: sgtty.h removed
+OLD_FILES+=usr/include/sgtty.h
 # 20080719: sade(8) removed on all but amd64, i386 and sparc64
 .if ${TARGET_ARCH} != "amd64" && ${TARGET_ARCH} != "i386" && \
     ${TARGET_ARCH} != "sparc64"

include/Makefile

@@ -18,7 +18,7 @@ INCS=	a.out.h ar.h assert.h bitstring.h complex.h cpio.h _ctype.h ctype.h \
 	netdb.h nl_types.h nlist.h nss.h nsswitch.h paths.h \
 	printf.h proc_service.h pthread.h \
 	pthread_np.h pwd.h ranlib.h readpassphrase.h regex.h regexp.h \
-	res_update.h resolv.h runetype.h search.h setjmp.h sgtty.h \
+	res_update.h resolv.h runetype.h search.h setjmp.h \
 	signal.h spawn.h stab.h \
 	stdbool.h stddef.h stdio.h stdlib.h string.h stringlist.h \
 	strings.h sysexits.h tar.h tgmath.h \

include/sgtty.h

@@ -1,3 +0,0 @@
-/* $FreeBSD$ */
-#error "The sgtty interface has been replaced by termios(4)"
-#error "Try to use <sys/ioctl.h> or migrate to <termios.h>"