Easier override of FILWIDTH_PIN

Marlin/pins_CHEAPTRONICv2.h

 //
 // Other board specific pins
 //
-#define FILWIDTH_PIN       37
 #define LED_PIN            13
 #define SPINDLE_ENABLE_PIN  4
 #define FAN_PIN             3
 #define PS_ON_PIN          45
 #define KILL_PIN           46
+
+#ifndef FILWIDTH_PIN
+  #define FILWIDTH_PIN     37   // should be Analog Input (0-15)
+#endif

Marlin/pins_PRINTRBOARD.h

 // Misc. Functions
 //
 #define SDSS               26
-#define FILWIDTH_PIN        2   // Analog Input
+
+#ifndef FILWIDTH_PIN
+  #define FILWIDTH_PIN      2   // Analog Input
+#endif
 
 //
 // LCD / Controller

Marlin/pins_PRINTRBOARD_REVF.h

 // Misc. Functions
 //
 #define SDSS               20 // Teensylu pin mapping
-#define FILWIDTH_PIN        2 // Analog Input
+
+#ifndef FILWIDTH_PIN
+  #define FILWIDTH_PIN      2   // Analog Input
+#endif
 
 //
 // LCD / Controller

Marlin/pins_RAMBO.h

 //
 #define SDSS               53
 #define LED_PIN            13
-#define FILWIDTH_PIN        3   // Analog Input
 #define PS_ON_PIN           4
 #define CASE_LIGHT_PIN     46
 
+#ifndef FILWIDTH_PIN
+  #define FILWIDTH_PIN      3   // Analog Input
+#endif
+
 //
 // LCD / Controller
 //

Marlin/pins_SCOOVO_X9H.h

 #define SDSS                53
 #define LED_PIN             13
 #define PS_ON_PIN            4
-#define FILWIDTH_PIN         3   // Analog Input
+
+#ifndef FILWIDTH_PIN
+  #define FILWIDTH_PIN       3   // Analog Input
+#endif
 
 //
 // LCD / Controller