Fix -Woverloaded-virtual warnings in ICU.

source/i18n/windtfmt.h

 /*
 ********************************************************************************
 *   Copyright (C) 2005-2013, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 ********************************************************************************
 *
 * File WINDTFMT.H
 *
 ********************************************************************************
 */
@@ skipping 34 matching lines @@
     Win32DateFormat(const Win32DateFormat &other);
 
     virtual ~Win32DateFormat();
 
     virtual Format *clone(void) const;
 
     Win32DateFormat &operator=(const Win32DateFormat &other);
 
     UnicodeString &format(Calendar &cal, UnicodeString &appendTo, FieldPosition &pos) const;
 
-    UnicodeString& format(UDate date, UnicodeString& appendTo) const;
-
     void parse(const UnicodeString& text, Calendar& cal, ParsePosition& pos) const;
 
     /**
      * Set the calendar to be used by this date format. Initially, the default
      * calendar for the specified or default locale is used.  The caller should
      * not delete the Calendar object after it is adopted by this call.
      *
      * @param calendarToAdopt    Calendar object to be adopted.
      */
     virtual void adoptCalendar(Calendar* calendarToAdopt);
@@ skipping 53 matching lines @@
 
     UnicodeString *fDateTimeMsg;
     DateFormat::EStyle fTimeStyle;
     DateFormat::EStyle fDateStyle;
     Locale fLocale;
     int32_t fLCID;
     UnicodeString fZoneID;
     TIME_ZONE_INFORMATION *fTZI;
 };
 
-inline UnicodeString &Win32DateFormat::format(UDate date, UnicodeString& appendTo) const {
-    return DateFormat::format(date, appendTo);
-}
-
 U_NAMESPACE_END
 
 #endif /* #if !UCONFIG_NO_FORMATTING */
 
 #endif // U_PLATFORM_HAS_WIN32_API
 
 #endif // __WINDTFMT