Fixes#17766
Previously, opaque directory whiteouts on non-native
graphdrivers depended on the file order, meaning
files added with the same layer before the whiteout
file `.wh..wh..opq` were also removed.
If that file happened to have subdirs, then calling
chtimes on those dirs after unpack would fail the pull.
Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>