More advanced Rust build options

[rnewman]

We should evaluate LTO and other build options. This is worth a read:

https://lifthrasiir.github.io/rustlog/why-is-a-rust-executable-large.html

and the FAQ:

https://www.rust-lang.org/en-US/faq.html#why-do-rust-programs-have-larger-binary-sizes-than-C-programs

[bgrins]

The particular question in the faq appears to have changed, since the fragment doesn't work. This looks like the relevant part: https://www.rust-lang.org/en-US/faq.html#why-do-rust-programs-have-larger-binary-sizes-than-C-programs.

[rnewman]

Fixed, thanks!