#[cfg(savvy_test)] will raise warnings

[Hiroaki Yutani]

https://blog.rust-lang.org/2024/05/06/check-cfg.html

[Hiroaki Yutani]

warning: unexpected `cfg` condition name: `savvy_test`
   --> src\eval.rs:131:7
    |
131 | #[cfg(savvy_test)]
    |       ^^^^^^^^^^
    |
    = help: expected names are: `clippy`, `debug_assertions`, `doc`, `docsrs`, `doctest`, `feature`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `rustfmt`, `sanitize`, `sanitizer_cfi_generalize_pointers`, `sanitizer_cfi_normalize_integers`, `target_abi`, `target_arch`, `target_endian`, `target_env`, `target_family`, `target_feature`, `target_has_atomic`, `target_has_atomic_equal_alignment`, `target_has_atomic_load_store`, `target_os`, `target_pointer_width`, `target_thread_local`, `target_vendor`, `test`, `ub_checks`, `unix`, `windows`
    = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(savvy_test)");` to the top of the `build.rs`
    = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default

warning: unexpected `cfg` condition name: `savvy_test`
   --> src\sexp\integer.rs:463:7
    |
463 | #[cfg(savvy_test)]
    |       ^^^^^^^^^^
    |
    = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(savvy_test)");` to the top of the `build.rs`
    = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

warning: `savvy` (lib) generated 2 warnings
    Finished `release` profile [optimized] target(s) in 5.03s