getrlimit still returns -1 as 'max' when limit is unlimited and for RLIM_INFINITY because rlim_t is considered signed.

The zshell project decides whether rlim_t is signed/unsigned (and also whether it is long or long long) in the configure step: https://github.com/zsh-users/zsh/blob/8b84419f45298ee564bd6fa2b531c8991b2a1983/configure.ac#L1859

On Linux, rlim_t is unisnged long long so the conversion should be done using PyLong_FromUnsignedLongLong (for RLIM_INFINITY) and using 'KK' instead of 'LL' in 'rlimit2py'.

IMHO the best way to fix this is to add configure steps like in zsh and then adding ifdefs to resource.c - in rlimit2py and near PyModule_AddObject of RLIM_INFINITY