make_chroot: handle make.conf files in /etc and /etc/portage

Newer stages are putting config files into /etc/portage.  Make sure we
clean them out before setting up /etc.

At some point we should migrate to /etc/portage, but this version is
designed to work with our current code base.

BUG=chromium:218085
TEST=`cbuildbot chromiumos-sdk` passes

Change-Id: I3e88909f1d8d46cdb4eef811236abc52554348ec
Reviewed-on: https://gerrit.chromium.org/gerrit/46230
Reviewed-by: David James <davidjames@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/sdk_lib/make_chroot.sh b/sdk_lib/make_chroot.sh
index bea08ce..376a2c6 100755
--- a/sdk_lib/make_chroot.sh
+++ b/sdk_lib/make_chroot.sh
@@ -197,10 +197,10 @@
    # and a pointer to pre-built packages.
    # TODO: This should really be part of a profile in the portage.
    info "Setting up /etc/make.*..."
-   mv "${FLAGS_chroot}"/etc/make.conf{,.orig}
+   rm -f "${FLAGS_chroot}"/etc/{,portage/}make.{conf,profile}
+   mkdir -p "${FLAGS_chroot}/etc/portage"
    ln -sf "${CHROOT_CONFIG}/make.conf.amd64-host" \
      "${FLAGS_chroot}/etc/make.conf"
-   mv "${FLAGS_chroot}"/etc/make.profile{,.orig}
    ln -sf "${CHROOT_OVERLAY}/profiles/default/linux/amd64/10.0" \
      "${FLAGS_chroot}/etc/make.profile"
 
@@ -405,7 +405,6 @@
   INITIALIZE_CHROOT=1
 fi
 
-
 if ! early_enter_chroot bash -c 'type -P pbzip2' >/dev/null ; then
   # This chroot lacks pbzip2 early on, so we need to disable it.
   early_env+=(