The gst_h264_parse_pps() function dynamically allocates the slice
group ids map array, so that needs to be cleared before parsing a
new PPS NAL unit again, or when it is no longer needed.
Likewise, a clean copy to the internal NAL parser state needs to be
performed so that to avoid a double-free corruption.
https://bugzilla.gnome.org/show_bug.cgi?id=707282
Signed-off-by: Gwenole Beauchesne <gwenole.beauchesne@intel.com>