bug#9716: Patch for HTML5 auto-coding support

[Juri Linkov]

> please find attached patch that
>
> * added support for detecting encoding in HTML5 specified only as <meta
> charset=***>
>
> Implementation just makes http-equiv and content-type parts from HTML4
> encoding string optional.

The HTML5 specification says:

  Using a meta element with a charset attribute that specifies the encoding
  within the first 1024 bytes of the document. E.g. <meta charset="UTF-8">
  could be used to specify the UTF-8 encoding. This replaces the need for
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  although that syntax is still allowed.

that confirms that we should install the proposed patch.