Only rebuild fuzz binaries if necessary

[stze]

At the moment every fuzz execution is causing a rebuild of the binaries, even if nothing was changed. See:

https://github.com/srlabs/ziggy/blob/main/src/bin/cargo-ziggy.rs#L210-L211

Expected behaviour would be to check if we actually need to rebuild or not.

[stze]

One idea would be to check how cargo fingerprints a version to decide whether a rebuild is required or not.

https://github.com/rust-lang/cargo/blob/6c49ea91d261f3ccae049eab48654c1332280da9/src/cargo/core/compiler/fingerprint/mod.rs

[stze]

A more naive idea is to let the user decide when to build and when to run until a more elaborate solution was implemented to fingerprint if a rebuild is necessary

[louismerlin]

This was a wasm-build-specific issue, closing here :smile: