Fixing trivial warnings spotted by Mingw-2.0.0/gcc-3.2:

window.c:90: warning: `do_mouse_wheel_msg' declared `static' but never defined
Introduced in 1.185 [r1499]. This function doesn't appear to ever have
existed.

[originally from svn r2334]
[r1499 == d6016149bf]

window.c

@@ -87,7 +87,6 @@ static void init_fonts(int, int);
 static void another_font(int);
 static void deinit_fonts(void);
 static void set_input_locale(HKL);
-static int do_mouse_wheel_msg(UINT message, WPARAM wParam, LPARAM lParam);
 
 static int is_full_screen(void);
 static void make_full_screen(void);