Fix build failure by "x86_64-cros-linux-gnu not found."

The libc debug step in dev_image_util is broken on certain old branches.
Remove that because we don't need the debug symbol files in factory
branches.

BUG=chromium:940696
TEST=None

Change-Id: I25bc5f8dc712e8233f7638d6abe14762e080c56e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/1584199
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Commit-Queue: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
1 file changed