[MOVED FROM BAD 32/56] gst/deinterlace2/gstdeinterlace2.c: Don't use proxy_getcaps() but implement our own getcaps() function that doubles/h...

Original commit message from CVS:
* gst/deinterlace2/gstdeinterlace2.c: (gst_deinterlace2_init),
(gst_greatest_common_divisor), (gst_fraction_double),
(gst_deinterlace2_getcaps), (gst_deinterlace2_setcaps):
Don't use proxy_getcaps() but implement our own getcaps() function
that doubles/halfs the framerate if all fields should be sent out.