Stop GCC from complaining about unhandled enumeration values.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@21491 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/utils.cpp

@@ -1097,6 +1097,8 @@ extern long wxEncodingToCharset(wxFontEncoding encoding)
 
         case wxFONTENCODING_CP437:
             return OEM_CHARSET;
+        default: // fix GCC warning
+            return -1;
     }
 
     // no way to translate this encoding into a Windows charset