isomp4: Update edit list when re-writing moov

Correctly update any edit lists each time the moov is recalculated,
updating existing table entries if they already exist instead of just
adding new ones.
diff --git a/gst/isomp4/atoms.h b/gst/isomp4/atoms.h
index a548380..943dfd6 100644
--- a/gst/isomp4/atoms.h
+++ b/gst/isomp4/atoms.h
@@ -828,7 +828,7 @@
 void       atom_trak_add_samples       (AtomTRAK * trak, guint32 nsamples, guint32 delta,
                                         guint32 size, guint64 chunk_offset, gboolean sync,
                                         gint64 pts_offset);
-void       atom_trak_add_elst_entry    (AtomTRAK * trak, guint32 duration,
+void       atom_trak_set_elst_entry    (AtomTRAK * trak, gint index, guint32 duration,
                                         guint32 media_time, guint32 rate);
 guint32    atom_trak_get_timescale     (AtomTRAK *trak);
 guint32    atom_trak_get_id            (AtomTRAK * trak);