Turn an SV's UTF8 flag on. Equivalent to Encode::_utf8_on, but we don't have to load Encode.

Turn an SV's UTF8 flag off.

Upgrade a SV to UTF8, converting Latin1 if necessary. Equivalent to utf::upgrade().

Concatenate one scalar onto the end of the other, ignoring UTF-8 status of the second scalar. This is necessary because $not_utf8 . $utf8 results in a scalar which has been infected by the UTF-8 flag of the second argument.