A random peer from the gray peer list is selected and a connection is
made to check if the peer is alive.
If the connection and handshake are successful the peer is promoted to
the white peer list, in case of failure the peer is evicted from the
gray peer list.
The connection is closed after the check in either case.
On 32-bit MinGW-w64, time_t is int32_t. The existing code was serializing
time_t directly and implicitly assuming that time_t is int64_t. This commit
formalizes that assumption by serializing int64_t directly and casting to
time_t where appropriate.
Thanks go to greatwolf for reporting this issue.
monero-project/bitmonero#88