Remove unused code that used to handle protocol concatenation, i.e. trying

Remove unused code that used to handle protocol concatenation, i.e. trying
multiple protocols at the same time. We now cycle protocols individually
to autodetect, making this code no longer needed, and thus the support code
for it in make_setup_request() can be removed. See "[PATCH] remove transport
concatenation dead code" on mailinglist.

Originally committed as revision 15172 to svn://svn.ffmpeg.org/ffmpeg/trunk