Copter: add INAV error count to PM dataflash msg

ArduCopter/Log.pde

@@ -433,6 +433,7 @@ struct PACKED log_Performance {
     int16_t  pm_test;
     uint8_t i2c_lockup_count;
     uint16_t ins_error_count;
+    uint8_t inav_error_count;
 };
 
 // Write a performance monitoring packet
@@ -447,7 +448,8 @@ static void Log_Write_Performance()
         max_time         : perf_info_get_max_time(),
         pm_test          : pmTest1,
         i2c_lockup_count : hal.i2c->lockup_count(),
-        ins_error_count  : ins.error_count()
+        ins_error_count  : ins.error_count(),
+        inav_error_count : inertial_nav.error_count()
     };
     DataFlash.WriteBlock(&pkt, sizeof(pkt));
 }
@@ -794,7 +796,7 @@ static const struct LogStructure log_structure[] PROGMEM = {
     { LOG_COMPASS_MSG, sizeof(log_Compass),             
       "MAG", "hhhhhhhhh",    "MagX,MagY,MagZ,OfsX,OfsY,OfsZ,MOfsX,MOfsY,MOfsZ" },
     { LOG_PERFORMANCE_MSG, sizeof(log_Performance), 
-      "PM",  "BBHHIhBH",       "RenCnt,RenBlw,NLon,NLoop,MaxT,PMT,I2CErr,INSErr" },
+      "PM",  "BBHHIhBHB",    "RenCnt,RenBlw,NLon,NLoop,MaxT,PMT,I2CErr,INSErr,INAVErr" },
     { LOG_CMD_MSG, sizeof(log_Cmd),                 
       "CMD", "BBBBBeLL",     "CTot,CNum,CId,COpt,Prm1,Alt,Lat,Lng" },
     { LOG_ATTITUDE_MSG, sizeof(log_Attitude),