gst/wavenc/gstwavenc.c: Correctly handle width!=depth input.

gst/wavenc/gstwavenc.c: Correctly handle width!=depth input.

Original commit message from CVS:
* gst/wavenc/gstwavenc.c: (gst_wavenc_create_header_buf),
(gst_wavenc_sink_setcaps):
Correctly handle width!=depth input.
* gst/wavparse/gstwavparse.c:
Already export in the caps that width==8 uses unsigned samples and
everything else uses signed samples.