SERVER-13961 Add OperationContext argument to Client::Context

Time tracking and database access in Client::Context require access to the
OperationContext. Adding it as argument.

This is in preparation for removing LockState from Client.
SERVER-14388 Fixup detection of yaml-cpp system library

The use of --use-system-yaml was incorrectly searching for yaml-cpp
under the 'yaml' name.

Search for yaml-cpp instead.

Fixes: SERVER-14388

Signed-off-by: Benety Goh <benety@mongodb.com>
Merge remote-tracking branch 'upstream/master'