bug#11309: 24.1.50; Case problems with [:upper:] and Cyrillic, Greek

[Mattias Engdegård]

8 dec. 2020 kl. 17.10 skrev Andreas Schwab <schwab@linux-m68k.org>:

> The function uses that only as a boolean, so why not pass it as that?

Thanks for reading the patch! It's a micro-optimisation: passing it as a 
boolean would entail an unconditional comparison against Qnil, but it is only 
used for [:lower:] and [:upper:] which are used in a small fraction of 
character alternatives. Maybe there is a cleaner way to do this without making 
the code slower.