Issue with short option parsing

I think adcli has a bug which causes issues with short option parsing:

https://gitlab.freedesktop.org/realmd/adcli/-/blob/master/tools/tools.c#L77

Here, isalpha is called on an integer. isalpha requires the argument to be representable as an unsigned char. The values provided however can be greater than UCHAR_MAX, like https://gitlab.freedesktop.org/realmd/adcli/-/blob/master/tools/computer.c#L99 where enumerators > 1000 are specified.

In practice, this seems to cause short option clashes. In the derivative version on Ubuntu 20.04, we end up with --use-ldaps and --login-user both using -U as a short option, for example.