More overridable FIL_RUNOUT_PIN

Marlin/src/pins/pins_CHEAPTRONICv2.h

@@ -109,7 +109,9 @@
 //
 // Other board specific pins
 //
-#define FIL_RUNOUT_PIN     37   // board input labeled as F-DET
+#ifndef FIL_RUNOUT_PIN
+  #define FIL_RUNOUT_PIN   37   // board input labeled as F-DET
+#endif
 #define Z_MIN_PROBE_PIN    36   // additional external board input labeled as E-SENS (should be used for Z-probe)
 #define LED_PIN            13
 #define SPINDLE_ENABLE_PIN  4   // additional PWM pin 1 at JP1 connector - should be used for laser control too

Marlin/src/pins/pins_CNCONTROLS_12.h

@@ -91,7 +91,9 @@
 
 // Common I/O
 
-#define FIL_RUNOUT_PIN     18
+#ifndef FIL_RUNOUT_PIN
+  #define FIL_RUNOUT_PIN   18
+#endif
 //#define PWM_1_PIN          12
 //#define PWM_2_PIN          13
 //#define SPARE_IO           17

Marlin/src/pins/pins_RAMPS_RE_ARM.h

@@ -200,7 +200,9 @@
 #define SDSS              P1_23  // (53)
 
 // define digital pin 4 for the filament runout sensor. Use the RAMPS 1.4 digital input 4 on the servos connector
-#define FIL_RUNOUT_PIN    P1_18  // (4)
+#ifndef FIL_RUNOUT_PIN
+  #define FIL_RUNOUT_PIN  P1_18  // (4)
+#endif
 
 #define PS_ON_PIN         P2_12  // (12)