Fix shellcheck SC2230
> which is non-standard. Use builtin 'command -v' instead.

Once applied to everything concerning OpenWrt we can disable the busybox
feature `which` and save 3.8kB.

Signed-off-by: Paul Spooren <mail@aparcar.org>

Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Signed-off-by: Marijan Svalina <marijan.svalina@sartura.hr>
Signed-off-by: Luka Perkov <luka.perkov@sartura.hr>

Bump LXC package from 1.1.5 to 2.1.0. Version 2.x includes many
improvements and optimizations.

https://linuxcontainers.org/lxc/news/

Some tools like lxc-top are rewritten in C and are no longer broken and
dependent on lua.

Signed-off-by: Marko Ratkaj <marko.ratkaj@sartura.hr>

Signed-off-by: Luka Perkov <luka@openwrt.org>