Fix -Woverloaded-virtual warnings in ICU.

source/i18n/windtfmt.h

Index: source/i18n/windtfmt.h
diff --git a/source/i18n/windtfmt.h b/source/i18n/windtfmt.h
index 0c182f54e649d0a234eff428856c436c90623d23..3f6d666574ffd9e3dedb423f53609005f3d5d2cd 100644
--- a/source/i18n/windtfmt.h
+++ b/source/i18n/windtfmt.h
@@ -52,8 +52,6 @@ public:
 
     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;
 
     /**
@@ -127,10 +125,6 @@ private:
     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 */