Server Discovery and Monitoring Spec: "Once a server is connected, the
client MUST change its type to Unknown only after it has retried the
server once."

Coverity warns about time-of-check, time-of-use race in mongoc-dump.c.

Introduced by mistake while implementing CDRIVER-2190.

This reverts commit 997a8239.

This commit only solved some of the problem, not all

* evergreen-fix:
  CDRIVER-2074 Fix static linking evergreen matrix to fail on error

Server Selection Spec update for single-threaded drivers.

If a server is selected that has an existing connection that has been idle for
socketCheckIntervalMS, the driver MUST check the connection with the "ping"
command. If the ping succeeds, use the selected connection. If not, set the
server's type to Unknown and update the Topology Description according to the
Server Discovery and Monitoring Spec, and attempt once more to select a server.

Internal isMaster commands should not be compressed, but user triggered
isMaster is fair game. We previously had asserts to ensure no
non-compressable commands would get compressed, which this check
would hit. Now that check has been removed and no longer need for this
workaround

If a server is selected and its socket has not been used in 5 seconds,
check if the socket is still good and retry once if not.