Since dirac 0.5.0 the framerate in dirac is expressed as a rational number. Fix build and up requirement to 0.5.0, an...

Original commit message from CVS:
Since dirac 0.5.0 the framerate in dirac is expressed as a rational number. Fix build and up requirement to 0.5.0, and also pass parameters to gst_diracdec_link in the right order. (fixes #167959)