Make memset in calloc a tail call.
Get canonical name in getaddrinfo from hosts file for AF_INET (fixes 16077)

AF_INET lookup in hosts file uses _nss_files_gethostbyname2_r, which
is not capable of returning a canonical name if it has found one.
This change adds _nss_files_gethostbyname3_r, which wraps around
_nss_files_gethostbyname2_r and then returns result.h_name as the
canonical name.