Fix heap corruption on Windows exposed by the use-after free fix.

Fix heap corruption on Windows exposed by the use-after free fix.
reset_address_cache() could call free_known_addresses() on a struct
addrinfo * that was returned by getaddrinfo().  It seems safest to just
make a copy of the addresses returned by getaddrinfo() so we can always
use free_known_addresses() instead of trying to determine whether or
not we need to use freeaddrinfo().