Prevent filament runout false positives (#9946)

.travis.yml

   - opt_set POWER_SUPPLY 1
   - opt_enable PIDTEMPBED FIX_MOUNTED_PROBE Z_SAFE_HOMING ARC_P_CIRCLES CNC_WORKSPACE_PLANES CNC_COORDINATE_SYSTEMS
   - opt_enable REPRAP_DISCOUNT_SMART_CONTROLLER SDSUPPORT EEPROM_SETTINGS
-  - opt_enable BLINKM PCA9632 RGB_LED NEOPIXEL_LED AUTO_POWER_CONTROL
+  - opt_enable BLINKM PCA9632 RGB_LED NEOPIXEL_LED AUTO_POWER_CONTROL NOZZLE_PARK_FEATURE FILAMENT_RUNOUT_SENSOR
   - opt_enable AUTO_BED_LEVELING_LINEAR Z_MIN_PROBE_REPEATABILITY_TEST DEBUG_LEVELING_FEATURE SKEW_CORRECTION SKEW_CORRECTION_FOR_Z SKEW_CORRECTION_GCODE
-  - opt_enable_adv FWRETRACT MAX7219_DEBUG LED_CONTROL_MENU CASE_LIGHT_ENABLE CASE_LIGHT_USE_NEOPIXEL CODEPENDENT_XY_HOMING
+  - opt_enable_adv FWRETRACT MAX7219_DEBUG LED_CONTROL_MENU CASE_LIGHT_ENABLE CASE_LIGHT_USE_NEOPIXEL CODEPENDENT_XY_HOMING ADVANCED_PAUSE_FEATURE
   - opt_set ABL_GRID_POINTS_X 16
   - opt_set ABL_GRID_POINTS_Y 16
   - opt_set_adv FANMUX0_PIN 53

Marlin/src/feature/runout.cpp

 
 FilamentRunoutSensor runout;
 
-bool FilamentRunoutSensor::filament_ran_out; // = false;
+bool FilamentRunoutSensor::filament_ran_out; // = false
+uint8_t FilamentRunoutSensor::runout_count; // = 0
 
 void FilamentRunoutSensor::setup() {
 

Marlin/src/feature/runout.h

 
 #include "../inc/MarlinConfig.h"
 
+#define FIL_RUNOUT_THRESHOLD 5
+
 class FilamentRunoutSensor {
   public:
     FilamentRunoutSensor() {}
 
     static void setup();
 
-    FORCE_INLINE static void reset() { filament_ran_out = false; }
+    FORCE_INLINE static void reset() { runout_count = 0; filament_ran_out = false; }
 
     FORCE_INLINE static void run() {
       if ((IS_SD_PRINTING || print_job_timer.isRunning()) && check() && !filament_ran_out) {
     }
   private:
     static bool filament_ran_out;
+    static uint8_t runout_count;
 
     FORCE_INLINE static bool check() {
       #if NUM_RUNOUT_SENSORS < 2
         // A single sensor applying to all extruders
-        return READ(FIL_RUNOUT_PIN) == FIL_RUNOUT_INVERTING;
+        const bool is_out = READ(FIL_RUNOUT_PIN) == FIL_RUNOUT_INVERTING;
       #else
         // Read the sensor for the active extruder
+        bool is_out;
         switch (active_extruder) {
-          case 0: return READ(FIL_RUNOUT_PIN) == FIL_RUNOUT_INVERTING;
-          case 1: return READ(FIL_RUNOUT2_PIN) == FIL_RUNOUT_INVERTING;
+          case 0: is_out = READ(FIL_RUNOUT_PIN) == FIL_RUNOUT_INVERTING; break;
+          case 1: is_out = READ(FIL_RUNOUT2_PIN) == FIL_RUNOUT_INVERTING; break;
           #if NUM_RUNOUT_SENSORS > 2
-            case 2: return READ(FIL_RUNOUT3_PIN) == FIL_RUNOUT_INVERTING;
+            case 2: is_out = READ(FIL_RUNOUT3_PIN) == FIL_RUNOUT_INVERTING; break;
             #if NUM_RUNOUT_SENSORS > 3
-              case 3: return READ(FIL_RUNOUT4_PIN) == FIL_RUNOUT_INVERTING;
+              case 3: is_out = READ(FIL_RUNOUT4_PIN) == FIL_RUNOUT_INVERTING; break;
               #if NUM_RUNOUT_SENSORS > 4
-                case 4: return READ(FIL_RUNOUT5_PIN) == FIL_RUNOUT_INVERTING;
+                case 4: is_out = READ(FIL_RUNOUT5_PIN) == FIL_RUNOUT_INVERTING; break;
               #endif
             #endif
           #endif
         }
       #endif
-      return false;
+      return (is_out ? ++runout_count : (runout_count = 0)) > FIL_RUNOUT_THRESHOLD;
     }
 };