812037cb80f72096738cf2b0c15b39536c6c1e24 Change CSipHasher's count variable to uint8_t (Pieter Wuille)
Pull request description:
SipHash technically supports arbitrarily long inputs (at least, I couldn't find a limit in the [paper](https://eprint.iacr.org/2012/351.pdf)), but only the low 8 bits of the length matter. Because of that we should use an unsigned type to track the length (as any signed type could overflow, which is UB). `uint8_t` is sufficient, however.
Fixes#19930.
ACKs for top commit:
laanwj:
anyhow re-ACK 812037cb80f72096738cf2b0c15b39536c6c1e24
elichai:
utACK 812037cb80f72096738cf2b0c15b39536c6c1e24
practicalswift:
ACK 812037cb80f72096738cf2b0c15b39536c6c1e24
theStack:
ACK 812037cb80f72096738cf2b0c15b39536c6c1e24
Tree-SHA512: 5b1440c9e4591460da198991fb421ad47d2d96def2014e761726ce361aa9575752f2c4085656e7e9badee3660ff005cc76fbd1afe4848faefe4502f3412bd896
