Very slow performances when asking an `Arbitrary` implementation to fuzz_target

[Tpt]

Thank you so much for this amazing library!

Sorry for polluting your bug tracker with a question.

This change doing an explicit T::arbitrary call inside of fuzz_target!(arg: &[u8] instead of just using fuzz_target!(arg: T seems to allow the fuzzer to try ~500x more valid inputs: oxigraph/oxigraph#509

Is there a reason why fuzz_target!(arg: T could be way slower than fuzz_target!(arg: &[u8] { let arg = T::arbitrary(&mut Unstructured::new(data));?

[Tpt]

Thanks to @adamreichold for the explanation on oxigraph/oxigraph#509