Add Perl_foldEQ_latin1()

Add Perl_foldEQ_latin1()

This function compares two non-utf8 strings to see if they are
equivalent without regards to case differences.  It does not work nor
check for  three problematic code points that require special handling:
MICRO_SIGN, LATIN_SMALL_LETTER_SHARP_S, and
LATIN_SMALL_LETTER_Y_WITH_DIAERESIS.

make regen required