AP_HAL_ChibiOS: log accumulated power status flags; all flags ever set

libraries/AP_HAL_ChibiOS/AnalogIn.cpp

@@ -473,6 +473,7 @@ void AnalogIn::update_power_flags(void)
         // the power status has changed while armed
         flags |= MAV_POWER_STATUS_CHANGED;
     }
+    _accumulated_power_flags |= flags;
     _power_flags = flags;
 }
 #endif // HAL_USE_ADC

libraries/AP_HAL_ChibiOS/AnalogIn.h

@@ -61,6 +61,7 @@ public:
     float board_voltage(void) override { return _board_voltage; }
     float servorail_voltage(void) override { return _servorail_voltage; }
     uint16_t power_status_flags(void) override { return _power_flags; }
+    uint16_t accumulated_power_status_flags(void) const override { return _accumulated_power_flags; }
     static void adccallback(ADCDriver *adcp);
 
 private:
@@ -74,6 +75,8 @@ private:
     float _servorail_voltage;
     float _rssi_voltage;
     uint16_t _power_flags;
+    uint16_t _accumulated_power_flags;  // bitmask of all _power_flags ever set
+
     ADCConversionGroup adcgrpcfg;
 
     struct pin_info {