libansilove: update to 1.2.3.

ChangeLog:

libansilove 1.2.3 (2020-05-25)

- Call memset() to set all fontData struct fields to zero in all loaders
- Refactor error handling in ansilove_savefile()
- Add error handling for fwrite() in ansilove_savefile()
- Fix includes in various source files

(fcambus)