Fix printer reset when changing filament during print over USB.

Firmware/Marlin.h

@@ -348,6 +348,7 @@ extern bool sortAlpha;
 
 extern char dir_names[3][9];
 
+extern int8_t lcd_change_fil_state;
 // save/restore printing
 extern bool saved_printing;
 

Firmware/ultralcd.cpp

@@ -35,7 +35,6 @@
 
 #include "mmu.h"
 
-extern int lcd_change_fil_state;
 extern bool fans_check_enabled;