chore: Convert delimiter to byte (#10570)

* Convert delimiter to byte

This commit converts the delimiter to byte from char. In some instances a char
can be multi-bytes wide, meaning that it's possible for the current algorithm to
split a delimiter as it forwards in the underlying buffer. The implementation
assumes that we want single-byte delimiters, which is now the case.

Resolves #10569

Signed-off-by: Brian L. Troutwine <brian@troutwine.us>

* correct benchmark ding

Signed-off-by: Brian L. Troutwine <brian@troutwine.us>