lang/gcc6-aux: Adopt and unbreak with isl 20+ (+)

Take maintainership and keep ada in the tree.

lang/gcc6-aux/Makefile

@@ -7,17 +7,13 @@ MASTER_SITES=	http://downloads.dragonlace.net/src/:boot \
 		LOCAL/marino:boot LOCAL/ericbsd:boot GCC/${MS_SUBDIR}
 DISTFILES=	${IDENTIFICATION}.tar.xz
 
-MAINTAINER=	ports@FreeBSD.org
+MAINTAINER=	fluffy@FreeBSD.org
 COMMENT=	Version of GCC ${GCC_BRANCH} with full Ada support
 WWW=		http://www.dragonlace.net/
 
 LICENSE=	GPLv3 GPLv3RLE
 LICENSE_COMB=	multi
 
-# PR 248674
-DEPRECATED=	Based on way end-of-life version of GCC, has issues, and is unmaintained
-EXPIRATION_DATE=2022-12-31
-
 .include "${.CURDIR}/Makefile.common"
 
 LANGS=			c c++ ada

lang/gcc6-aux/Makefile.version

@@ -8,7 +8,7 @@ GCC_POINT=		4.1
 GCC_VERSION=		${GCC_BRANCH}.${GCC_POINT}
 SNAPSHOT=		20180516
 BUILD_RELEASE=		no
-MAIN_PR=		2
+MAIN_PR=		3
 UTIL_PR=		0
 ARMV7_PR=		0
 ARM64_PR=		0

lang/gcc6-aux/files/patch-isl-20-or-newer

@@ -0,0 +1,11 @@
+--- gcc/graphite.h.orig	2020-08-15 14:22:45.859708000 -0400
++++ gcc/graphite.h	2020-08-15 14:25:15.832648000 -0400
+@@ -36,6 +36,8 @@
+ #include <isl/ilp.h>
+ #include <isl/schedule.h>
+ #include <isl/ast_build.h>
++#include <isl/id.h>
++#include <isl/space.h>
+ 
+ #ifdef HAVE_ISL_OPTIONS_SET_SCHEDULE_SERIALIZE_SCCS
+ /* isl 0.15 or later.  */