This might not be needed at the moment, but it's good practice to
pass it to all chained AVFormatContexts, if it would happen to be
used there at a later point.
Signed-off-by: Martin Storsjö <martin@martin.st>
Provide a way to wrap around the segment index so pseudostreaming
live through a web server and html5 browser is simpler.
Also ensure that 0 (disable) is a valid value across the options
providing wrap around.