buildhistory: Fix do_package race issues

The buildhistory_list_pkg_files function uses data from do_package, not
do_packagedata. Usally the two are restored together but it may see
a half complete directory or other races issues depending on timing.

Rework the function so that it uses the correct task dependencies. This
should avoid races but means the data is only restored to buildhistory
if the do_package or do_package_setscene tasks are restored.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>