make_chroot: Remove unused toolchain overlay support

cros_sdk can pass in an additional overlay tarball to unpack on top of
the chroot.  This hasn't been used in cros_sdk since 2016 and is being
removed, so no need to support it in make_chroot.sh, either.

BUG=chromium:845174
TEST=cros_sdk --create
CQ-DEPEND=CL:1081389

Change-Id: I1f585fd5f2d0991c43b804f30d34c2a0a68337a6
Reviewed-on: https://chromium-review.googlesource.com/1081339
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Benjamin Gordon <bmgordon@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/sdk_lib/make_chroot.sh b/sdk_lib/make_chroot.sh
index 4191dc8..cfff479 100755
--- a/sdk_lib/make_chroot.sh
+++ b/sdk_lib/make_chroot.sh
@@ -43,8 +43,6 @@
   "Use the stage3 with the given date."
 DEFINE_string stage3_path "" \
   "Use the stage3 located on this path."
-DEFINE_string toolchains_overlay_path "" \
-  "Use the toolchains overlay located on this path."
 DEFINE_string cache_dir "" "Directory to store caches within."
 DEFINE_boolean useimage $FLAGS_FALSE "Mount the chroot on a loopback image."
 
@@ -512,10 +510,6 @@
 else
   info "Unpacking stage3..."
   unpack_tarball "${FLAGS_stage3_path}" "${FLAGS_chroot}"
-  if [[ -n "${FLAGS_toolchains_overlay_path}" ]]; then
-    info "Unpacking toolchains overlay..."
-    unpack_tarball "${FLAGS_toolchains_overlay_path}" "${FLAGS_chroot}"
-  fi
   rm -f "$FLAGS_chroot/etc/"make.{globals,conf.user}
 fi