gst/qtdemux/qtdemux.c: In push mode, error out if we get EOS before we've created...

gst/qtdemux/qtdemux.c: In push mode, error out if we get EOS before we've created any srcpads.

Original commit message from CVS:
* gst/qtdemux/qtdemux.c:
In push mode, error out if we get EOS before we've created any srcpads.
Handle (in pull mode) some files that have a truncated moov atom where
the final sub-atom is a 'free' atom and the contents of that are not
present in the file.