rust: Set release profile settings

rust: Set release profile settings

* codegen-units, lto, opt-level - Set to values to optimize binary
  size[1].

* overflow-checks - Enabled because in release mode, integer overflows
  are defined as two's complement wrap[2]. It is highly unlikely that
  any program is intentionally relying on this behaviour; it would be
  better to panic instead of continue execution in this case.

* debug, debug-assertions, panic, rpath - Set to their default (release)
  values, to override any settings made by packages, e.g. ripgrep sets
  debug = 1[3].

[1]: https://github.com/johnthagen/min-sized-rust
[2]: https://huonw.github.io/blog/2016/04/myths-and-legends-about-integer-overflow-in-rust/
[3]: https://github.com/BurntSushi/ripgrep/blob/13.0.0/Cargo.toml#L79-L80

Signed-off-by: Jeffery To <jeffery.to@gmail.com>