Update to the 20181017 snapshot of GCC 6.4.1.

This now includes files/patch-libgfortran directly (which I pushed and
backported upstream), so remove our local copy.

lang/gcc6-devel/Makefile

@@ -2,7 +2,7 @@
 # $FreeBSD$
 
 PORTNAME=	gcc
-PORTVERSION=	6.4.1.s20181010
+PORTVERSION=	6.4.1.s20181017
 CATEGORIES=	lang java
 MASTER_SITES=	GCC/snapshots/${DIST_VERSION}
 PKGNAMESUFFIX=	${SUFFIX}-devel

lang/gcc6-devel/distinfo

@@ -1,3 +1,3 @@
-TIMESTAMP = 1539499387
-SHA256 (gcc-6-20181010.tar.xz) = 0396dc43a259d6d4828e62e352f822a37b84435fe7ede4d64bb514e5c07877a0
-SIZE (gcc-6-20181010.tar.xz) = 72686384
+TIMESTAMP = 1539974651
+SHA256 (gcc-6-20181017.tar.xz) = 5396a3877a19e314db33943f9d63a2516ef867cc95912e96234ba7bf34a22cbc
+SIZE (gcc-6-20181017.tar.xz) = 72693488

lang/gcc6-devel/files/patch-libgfortran

@@ -1,19 +0,0 @@
-2018-10-02  Gerald Pfeifer  <gerald@pfeifer.com>
-
-	* io/close.c [!HAVE_UNLINK_OPEN_FILE]: Include <string.h>.
-
---- UTC
-Index: libgfortran/io/close.c
-===================================================================
---- libgfortran/io/close.c	(revision 264799)
-+++ libgfortran/io/close.c	(revision 264800)
-@@ -26,6 +26,9 @@ see the files COPYING3 and COPYING.RUNTIME respect
- #include "unix.h"
- #include "async.h"
- #include <limits.h>
-+#if !HAVE_UNLINK_OPEN_FILE
-+#include <string.h>
-+#endif
- 
- typedef enum
- { CLOSE_DELETE, CLOSE_KEEP, CLOSE_UNSPECIFIED }