Add PerformanceLoss threshold checking

This xyz.openbmc_project.Sensor.Threshold.PerformanceLoss interface will
be checked along with the other threshold interfaces.  It can be used to
indicate the system will suffer a performance loss when the sensor goes
above/below the high/low threshold values.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I855aaf6ea550e672bf52af5631533049269934d1
diff --git a/virtualSensor.hpp b/virtualSensor.hpp
index 4553024..ba802db 100644
--- a/virtualSensor.hpp
+++ b/virtualSensor.hpp
@@ -115,6 +115,8 @@
     std::unique_ptr<Threshold<SoftShutdownObject>> softShutdownIface;
     /** @brief The hard shutdown threshold interface object */
     std::unique_ptr<Threshold<HardShutdownObject>> hardShutdownIface;
+    /** @brief The performance loss threshold interface object */
+    std::unique_ptr<Threshold<PerformanceLossObject>> perfLossIface;
 
     /** @brief Read config from json object and initialize sensor data
      * for each virtual sensor