Bug#968040: Patch pppd to handle Windows Server 2019 non-compliant success packets

[Douglas Kosovic]

macOS already handles the missing space before M= with code that does similar 
to the upstream ppp patch, extract from :
https://opensource.apple.com/source/ppp/ppp-862.120.2/Helpers/pppd/chap_ms.c.auto.html

        //we'll allow the missing-space case from the server, even though
        //it's non-conforming to spec!
        dbglog("Rcvd non-conforming MSCHAPv2 Success packet, len=%d", len);
        if(len >= 2 && !strncmp((char*)msg, "M=", 2))
                msg += 2;
        else
        {
                error("MS-CHAPv2 Success packet is badly formed.");
                return 0;
        }