Bug#612675: libkio5: KTar class have broken UTF-8 support(longlink)

[Ibragimov Rinat <ibragimovrinat@mail.ru>]

> Well, ok, but that still does not explain why you cast one "check" to 
> (unsigned char) leaving others untouched. QByteArray::operator[] also returns 
> a _signed_ char. So what makes you think those chars will always be <= 127 ?
> 

Um, yes, you're right. I missed code that reads tar files. There must be (unsigned char)
cast too.

There are also another uses of buffer as signed char, for checksum fields, but those 
bytes may contain only ' ', numbers, and '\0'. All of them lower than 128, so no casting
is required. But maybe I should add them for consistency.