Enable debug-assertions in release builds.
Enable debug-assertions in release builds.

We really want to build with, at least, -Z force-overflow-checks=on to
catch integer over/underflows.  Given that it doesn't seem possible to
do this via Cargo without forcing users to build with "cargo rustc",
enabling debug-assertions gives us what we want (and slightly more).

kinetiknz/mp4parse-rust,kinetiknz/mp4parse-rust,mozilla/mp4parse-rust