mp4parse_capi: Make mp4parse_byte_data take slice references.
mp4parse_capi: Make mp4parse_byte_data take slice references.

The slice primitive type implements len() and as_ptr() so
we can accept a slice reference instead of a Vec reference.

This is more general and resolves a clippy warning.

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