Added explicit 'void' to function that takes no argument

This is the correct way to tell that a function takes no
arguments, because an empty parameter list tells the compiler
that it is not yet defined, and is tolerated only for
compatibility with very old C compilers for whom prototypes
were not yet a defined language element.

src/keybind.h

@@ -122,6 +122,6 @@ typedef struct WShortKey {
     KeyCode keycode;
 } WShortKey;
 
-void wKeyboardInitialize();
+void wKeyboardInitialize(void);
 
 #endif /* WMKEYBIND_H */