ffmpeg: don't use av_log_ask_for_sample()

Deprecated. Use a local ask_for_sample wrapper instead.

Signed-off-by: Reynaldo H. Verdejo Pinochet <reynaldo@osg.samsung.com>
ffserver: deprecate Port and BindAddress options in favor of HTTPPort and HTTPBindAddress

The new option names are more explicit.

Signed-off-by: Reynaldo H. Verdejo Pinochet <reynaldo@osg.samsung.com>