gopher: Do not translate `?' to `%09'

Since GOPHER support was added in curl `?' character was automatically
translated to `%09' (`\t').

However, this behaviour does not seems documented in RFC 4266 and for
search selectors it is documented to directly use `%09' in the URL.
Apart that several gopher servers in the current gopherspace have CGI
support where `?' is used as part of the selector and translating it to
`%09' often leads to surprising results.

Closes #2910