unit-tests: Fix `cargo test` on 32-bit platforms
Fixes https://bz.mercurial-scm.org/show_bug.cgi?id=6506
This makes `IndexEntryBuilder::build`, which is only used in unit tests, use
`u32` or `u64` instead of platform-dependent `usize` when packing binary data
to be used at test input.
To run Rust unit tests in 32-bit mode in a x86-64 environment, use:
rustup target add i686-unknown-linux-gnu # Once
(cd rust && cargo test --target i686-unknown-linux-gnu)
Differential Revision: https://phab.mercurial-scm.org/D10351
Greg Ward, author of the original bfiles extension
Na'Tosha Bard of Unity Technologies
Fog Creek Software
Special thanks to the University of Toronto and the UCOSP program