$NetBSD$

Support Darwin/aarch64, from https://github.com/Homebrew/formula-patches.

--- /dev/null
+++ gcc/config/aarch64/t-aarch64-darwin
@@ -0,0 +1,25 @@
+# Machine description for AArch64 architecture.
+#  Copyright (C) 2020 Free Software Foundation, Inc.
+#
+#  This file is part of GCC.
+#
+#  GCC is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 3, or (at your option)
+#  any later version.
+#
+#  GCC is distributed in the hope that it will be useful, but
+#  WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+#  General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with GCC; see the file COPYING3.  If not see
+#  <http://www.gnu.org/licenses/>.
+
+LIB1ASMSRC   = aarch64/lib1funcs.asm
+LIB1ASMFUNCS = _aarch64_sync_cache_range
+
+# TODO - figure out what multilib provisions we should make for
+# a) arm64e
+# b) arm64_32
