Change name of regex intrnl macro to new meaning

Change name of regex intrnl macro to new meaning

ANYOF_FOLD is now used only under fewer conditions.  Otherwise the
bitmap of character 0-255 is fully calculated with the folds, and the
flag is not set.  One condition is under locale, where the folds aren't
known at compile time; the other is for things accessible through a
swash.

By changing the name to its new meaning, certain optimizations become more
obvious.