Assuming a particular width of a type (or equivalence with "long") doesn't
work everywhere.  On new architectures, LFS/etc is enabled by default,
making rlim_t same as rlim64_t even if long is only 32-bit.

Not sure how you handle too big values -- you may want to re-check the
strtoull part.
Signed-off-by: Adam Borowski <kilobyte@angband.pl>