* CDRIVER-1961-improve-gssapi-error-message:
  CDRIVER-1961 Improve error message when GSSAPI module not available

Fixes a timeout in /Socket/sendv test.

The test had wrongly assumed that a sendv timeout set socket->errno_,
but this errno was actually set from the initial call to accept or
connect. These functions do not set socket->errno_ during this test of
localhost connections on FreeBSD, the way they do on Mac and Linux.

Keys in documents for insert, save, or replace must not contain "." or start with "$". Keys in documents for update must all start with "$".

Fix the Application Performance Monitoring implementation. A series of commands
could be monitored with the same operation_id. Now we generate unique ids.

Also, a series of commands related to the same mongoc_bulk_operation_t could
have different ids. Now, we monitor all commands for one bulk operation with
the same id.