Fix unicode version of integrable function symbol to match GIF version.
Fix unicode version of integrable function symbol to match GIF version.

The I tags as given were causing each symbol after the L in the current statement's cell (in metamath's ALT_HTML export) or in *all lines* after (in mmj2's GMFF-exported althtml pages).

metamath/set.mm,metamath/set.mm,metamath/set.mm