pvr: fix duplicate EPG IDs if EPG is not stored in database
ff_id3v2_free_extra_meta: set the pointer pointing to extra_meta to NULL

Fixes ticket #3530.

Signed-off-by: Peter Ross <pross@xvid.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
FFmpeg: Cherry-pick c94305ae23318c8956a30485cd5642829f4f16a9 to fix #15085
Merge pull request #4583 from fritsch/xbmc-upstream

ffmpeg: Backport c94305ae23318c8956a30485cd5642829f4f16a9 to fix #15085
Merge pull request #4581 from FernetMenta/epg

pvr: fix duplicate EPG IDs if EPG is not stored in database
videoplayer: adapt lateness detection and dropping to buffering
video player: present correct pts to user for a/v sync (after buffering in renderer)
videoplayer: some rework and documentation
renderer: bump buffers to 5
videoplayer: update frametime, it might change due to fps detection
videoplayer: give streams with invalid fps a chance for fps detection
dvdplayer: allow rewinding at end of stream, do a seek after rewind
X11: ditch SDL for video and window events
X11: Add xbmc icon
X11: add SDL joystick until we have a better solution
X11: factor out code handling device reset notification
X11: move xrandr events to WinEventsX11
xrandr: remove method RestoreState
xrandr: observe orientation
xrandr: allow getting info for multiple screen's

Refactored by: Joakim Plate <elupus@xbmc.org>