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.

Fixes issue #544 (closed)