charclass_invlists.h: Add some inverse folds.

charclass_invlists.h: Add some inverse folds.

The MICRO SIGN folds to above the Latin1 range, the only character that
does so in Unicode (or ever likely to).  This requires special handling.
This commit reduces some of the need for that handling by creating the
inversion map for it, which can be used in certain instances in pattern
matching, without having to have a special case.  The actual use of this
will come in a future commit.