ext/gdk_pixbuf/gstgdkpixbuf.c: Fix logic bug causing spurious errors.

ext/gdk_pixbuf/gstgdkpixbuf.c: Fix logic bug causing spurious errors.

Original commit message from CVS:
* ext/gdk_pixbuf/gstgdkpixbuf.c: (gst_gdk_pixbuf_sink_link),
(gst_gdk_pixbuf_chain): Fix logic bug causing spurious errors.
* ext/jpeg/gstjpegdec.c: (gst_jpegdec_base_init),
(gst_jpegdec_init), (gst_jpegdec_chain): Fix negotiation.
* ext/jpeg/gstjpegenc.c: (gst_jpegenc_base_init),
(gst_jpegenc_class_init), (gst_jpegenc_init),
(gst_jpegenc_getcaps), (gst_jpegenc_link), (gst_jpegenc_resync),
(gst_jpegenc_chain), (gst_jpegenc_set_property),
(gst_jpegenc_get_property):  Fix negotiation.  Add some properties.
* ext/jpeg/gstjpegenc.h: Fix negotiation.