Add hook to cleanup /etc/make.conf.board_setup in SDK

Remove references to amd64-host sysroot in make.conf.board_setup so it
can be used on the host.

BUG=b:193915549
TEST=update_chroot succeeds

Cq-Depend: chromium:3253130
Change-Id: I88a2a29c69f593abbf1b8d8d7a72dc1bc22d3bd2
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/3253802
Tested-by: Sloan Johnson <sloanjohnson@google.com>
Commit-Queue: Sloan Johnson <sloanjohnson@google.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/chroot_version_hooks.d/190_make_conf_board_setup_cleanup b/chroot_version_hooks.d/190_make_conf_board_setup_cleanup
new file mode 100644
index 0000000..c573cc9
--- /dev/null
+++ b/chroot_version_hooks.d/190_make_conf_board_setup_cleanup
@@ -0,0 +1,7 @@
+# Copyright 2021 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Remove vars that reference the amd64-host sysroot from
+# /etc/make.conf.board_setup for it to be correctly used in the SDK.
+sudo sed -E -i '/ROOT|PKG_CONFIG/d' /etc/make.conf.board_setup