kernel: keep legacy throne tracker as an option
This change restores older throne tracker that uses packages.list scanning
to track app UIDs. It's intended for ultra-legacy Linux 3.X kernels that
experience deadlocks or crashes with the newer implementation due to issues
in user_data_actor().
We have to remember that the whole iterate_dir, and filldir subsystem is way
different on 3.X.
Changes:
- CONFIG_KSU_THRONE_TRACKER_LEGACY in Kconfig
- conditional compilation in Makefile
- throne_tracker_legacy.c which keeps the old implementation
Enable this option if newer throne tracker (tiann #2757crashes on you.)
Co-authored-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
