Fix arch-dependent getnameinfo types

getnameinfo() parameters are detected by configure. Current glibc uses
socklen_t for BUFLEN and int for flags. Because that parameters are
tested only as fallback, it does detect it different way on 32-bit
system. socklen_t is compatible with size_t type on these systems.
Try all variants with int flags, use unsigned flags as last resort.

(cherry picked from commit b427dcce)
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