Weihang Lo fbb5b90fe0
test(build-std): make mock-std closer to real world
`test_std_on_unsupported_target` never really succeed to build those targets, due to

* local rustup may not have `{aarch64,x86_64}-unknown-none` installed.
* `core` and `compiler-builtins` mock crate are not `no_std` nor `no_core`
* the dummy `main.rs` uses `println!` and is not `no_std`.

This commit make it compile, if you have those targets installed.
2024-12-05 10:50:51 -05:00
..