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/moveres.c

@@ -535,7 +535,7 @@ static void drawFrames(WWindow * wwin, WMArray * array, int dx, int dy)
 	}
 }
 
-static void flushMotion()
+static void flushMotion(void)
 {
 	XEvent ev;