More overridable FIL_RUNOUT_PIN

Marlin/src/pins/pins_CHEAPTRONICv2.h

 //
 // 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

 
 // 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

 #endif
 
 #ifndef FAN_PIN
-  #define FAN_PIN         P1_18 // (4) IO pin. Buffer needed
+  #define FAN_PIN         P1_18  // (4) IO pin. Buffer needed
 #endif
 
 //
 // Misc. Functions
 //
-#define LED_PIN           P4_28 // (13)
-#define SDSS              P1_23 // (53)
+#define LED_PIN           P4_28  // (13)
+#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)
+#define PS_ON_PIN         P2_12  // (12)
 
 #if ENABLED(CASE_LIGHT_ENABLE) && !PIN_EXISTS(CASE_LIGHT) && !defined(SPINDLE_LASER_ENABLE_PIN)
   #if !defined(NUM_SERVOS) || NUM_SERVOS < 4 // try to use servo connector