Remove GBK -> X-GBK Alias and add X-GBK -> GBK

[pyatnitsev]

I have an Issue with decoding a message in GBK encoding, becouse it transform to X-GBK that not supported by iconv PHP function.

I saw this doc https://encoding.spec.whatwg.org/#encodings and this one https://dxr.mozilla.org/mozilla-central/source/dom/encoding/labelsencodings.properties and in the second document X-GBK should be transformed to GBK.

related issue #395

[Slamdunk]

Hi, you are right, Transcoder comes from https://dxr.mozilla.org/mozilla1.9.1/source/intl/uconv/src/charsetalias.properties which is mostly outdated by https://dxr.mozilla.org/mozilla-central/source/dom/encoding/labelsencodings.properties .

For the sake of completness, can you add to test or post here the original raw message that originated the issue (with sensitive data stripped out) please?

[pyatnitsev]

I see letter with eror, but if I print body of letter to console and copy that in variable (override $text and $fromCharset) it works well...
in body: <meta http-equiv="Content-Type" content="text/html; charset=gb2312">

[Slamdunk]

I need the output of $message->getRawMessage() please

[pyatnitsev]

Sorry, I can't remove all sensitive data from letter, but I have output of getRawMessage() function.
Do you need headers? I can post a part of message if it help you.

------=_Part_116476_1454027372.1548343396450
Content-Type: text/plain; charset=GBK
Content-Transfer-Encoding: base64

RGVhciAgc2lyIAoKCkkgdHJhZGUgc3RvY2tzIGluIEFtZXJpY2FuICBtYXJrZXQgZm9yIG1vcmUg
dGhhbiA1IHllYXJzIC4gIEkgd2FudCB0aGUgU3RlcmxpbmcgcGxhdGZvcm0gLiAgSSB3YW50IHRv

and begin of html-part:

------=_Part_116476_1454027372.1548343396450
Content-Type: text/html; charset=GBK
Content-Transfer-Encoding: base64

PG1ldGEgaHR0cC1lcXVpdj0iQ29udGVudC1UeXBlIiBjb250ZW50PSJ0ZXh0L2h0bWw7IGNoYXJz

I'm trying to reproduce this bug in my own letter sent with GBK encoding, but it works well