Some improvements in Makefile.mingw32.depend

- Change $(cce) to output .d file prerequisite too, the same as .o
- Replace $(CLEAN_FILE) handling w/ "clean: cleandep", for more encapsulation

include/windconf.h

@@ -228,9 +228,7 @@ extern void win32_abort(void);
 extern void consoletty_preference_update(const char *);
 extern void toggle_mouse_support(void);
 extern void map_subkeyvalue(char *);
-#if defined(WIN32CON)
 extern void set_altkeyhandling(const char *);
-#endif
 extern void raw_clear_screen(void);
 
 #include <fcntl.h>