ext/gdk_pixbuf/: Add new pixbufscale element to scale RGB video using gdk_pixbuf, because gdk_pixbuf does BILINEAR an...

Original commit message from CVS:
* ext/gdk_pixbuf/Makefile.am:
* ext/gdk_pixbuf/gstgdkpixbuf.c: (plugin_init):
* ext/gdk_pixbuf/gstgdkpixbuf.h:
Add new pixbufscale element to scale RGB video
using gdk_pixbuf, because gdk_pixbuf does BILINEAR
and HYPER interpolation correctly.
* ext/theora/theoraenc.c: (theora_enc_chain),
Discard buffer and return if explicit caps could not be set
(theora_enc_get_property):
Make _get return kbps for the bitrate consistent with
the _set function.