gst/wavparse/gstwavparse.c: Fix seeking in .wav files again (#501775).  Some people seem to think they don't need to ...

Original commit message from CVS:
* gst/wavparse/gstwavparse.c: (gst_wavparse_srcpad_event):
Fix seeking in .wav files again (#501775).  Some people seem to think
they don't need to test their changes when they're just 'reflowing'
some code.