- Add "lto": whole binary link time optimisation.
- Use opt-level = "z": to optimize for size.
- Make the panic handler simply abort() rather then unwinding and
   printing a backtrace.

Add flag in debian/rules to strip symbols from the binary.

Inspired by https://github.com/uutils/coreutils/commit/0c4f586



Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
Signed-off-by: Sjoerd Simons <sjoerd@collabora.com>
Signed-off-by: Dylan Aïssi <dylan.aissi@collabora.com>