oggdec: free the ogg streams on read_header failure

Plug an annoying memory leak on broken files.
(cherry picked from commit 89b51b570daa80e6e3790fcd449fe61fc5574e07)

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
oggdec: make sure the private parse data is cleaned up

(cherry picked from commit d894f74762bc95310ba23f804b7ba8dffc8f6646)

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>