src/main.c: Moved local prototype for global function to header 'funcs.h'

It is a bad idea to declare the prototype of an external function
in a file as it won't allow the compiler to cross-check it.

src/monitor.c

@@ -38,6 +38,7 @@
 #include "window.h"
 #include "dialog.h"
 #include "main.h"
+#include "funcs.h"
 
 /****** Global Variables ******/
 extern WPreferences wPreferences;