Causes several knock-on inspections in `OsuGame` et al. Probably best
addressed in a separate pass, because treatment is mixed at best (some
places nullcheck, some expect non-null).
As it turns out, on some cultures, the "negative integer" sign is not
encoded using the U+002D HYPHEN-MINUS codepoint. For instance, Swedish
uses U+2212 MINUS SIGN instead. This was confusing the legacy decoder,
since it is correctly depending on the serialisation being
culture-independent.
To fix, ensure that the special "end replay" frame, as well as the
replay MD5 hash, are generated in a culture-invariant manner.
Thankfully the replay MD5 hash is currently being discarded in
`LegacyScoreDecoder`, so it changing in future scores should not have
any negative effect on lazer operation.