BUILD: limits: make normalize_rlim() take an rlim_t to fix build on m68k

BUILD: limits: make normalize_rlim() take an rlim_t to fix build on m68k

As can be seen here, the build fails on m68k since commit 665dde648
("MINOR: debug: use LIM2A to show limits") in 3.1:

  https://github.com/haproxy/haproxy/actions/runs/12440234399/job/34735360177

The reason is the comparison between a ulong limit and RLIM_INFINITY.
Indeed, on m68k, rlim_t is an unsigned long long. Let's just change
the function's input type to take an rlim_t instead. This also allows
to get rid of the casts in the call place.

This can be backported to 3.1 though it's not important given the low
prevalence of this platform for such use cases.