Fix the timeout option not working when connecting to a HTTP url that requires authentication.

In http_open_cnx, the patch restores the AVDictionary if connection needs to be re-tried
because of a authentication/redirect status code.

Previously, if a 401/407/30x status code was encountered, http_open_cnx would restart at the redo label, but any options
used by the underlying protocol would be missing because they were removed by the first attempt.

Signed-off-by: Brandon Lees <brandon@n-hega.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/http: simplify chained_options copying

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>