QWindowsLocalCodec::canEncode() always succeeds

Write a code that will check to see if it can convert a UTF16 string into MultiByte in the current locale is not possible.

QTextCodec::canEncode() always succeeds because:

This code:

QByteArray QWindowsLocalCodec::convertFromUnicode(const QChar *uc, int len, ConverterState *) const 
{ 
    return qt_winQString2MB(uc, len); 
} 

does not use the converter state's 'invalidChars' param to be set to true if characters are replaced.

Edit: Testcase:

assert(!QTextCodec::codecForName("ASCII")->canEncode(QString::fromUtf8("t\xC3\xB6")));

It should be false since "tö" is encoded as "t?" with that codec.