Corrected type on bufputc

[andre-d]

~~Possible vulnerability~~ implicit cast, my bad

[andre-d]

Might be implicitly casted, good idea to correct anyway.

[andre-d]

Confirmed, implicit cast to char, still likely should be uint8_t or char to begin with.

[mildsunrise]

@andre-d :+1: anyway, your changes can't cleanly merge with master because they've different base commits. If you can add me to your repo, I'll fix this for you. Thanks!