regen/charset xlations.pl: Use revised UTF-8 macros

regen/charset xlations.pl: Use revised UTF-8 macros

I realized that two base level utf8.h macros for UTF-8 could be
refactored to eliminate the conditionals in each.  Those macros have
equivalents in the pure perl code changed by this commit, which I
changed before the utf8.h versions to verify that everything worked, by
verifying there was no difference in the generated tables.