SERVER-6514 Only apply -zdefs and --as-needed to shared client library
SERVER-6514 Don't attempt to test shared library clients for out of tree builds
SERVER-9338 ensure maintenanceMode properly decremented
-created MaintenanceModeSetter for setting maintenance mode
-used MaintenanceModeSetter to avoid incorrectly decrementing maintenance mode
-added assert in rs.cpp to confirm maintenance mode never goes negative