This was masking errors when the loadable object failed to load for some reason other than XSLoader being unavailable. The alternative was to only eval the load of XSLoader and keep the fallback, but XSLoader has been core perl for a while.
I plan to stop receiving mail on imager.perl.org eventually. Give myself a smaller attack surface for spammers.
change i_utf8_advance to accept the working length as a size_t and propagate that change through anything that uses it