Use of VAConfigAttribEncMaxRefFrames in h264encode.c

I'm looking into the h264encode.c example where the `VAConfigAttribEncMaxRefFrames` attribute is used to retrieve the number
of maximum reference frames. When this attribute is supported the value is not checked against the `num_ref_frames` variable. What happens if `num_ref_frames` is larger than the value in the `VAConfigAttribEncMaxRefFrames` attribute? The `num_ref_frames` is used in the SPS.