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>
1 file changed