Fix: pixel copy for RPR
Current SIMD code clips results of horizontal filtering for RPR as part of vertical pixel copy. The fix is to omit clipping in that case (isFirst==isLast). No impact on non-RPR. The reason for pixel copy working for non-RPR is that there is a check if xFrac or yFrac is 0 and then only one filtration is done. In non-RPR when yFrac is 0 horizontal pixel copy is always performed without clipping (isFirst always true and for bi-pred isLast is false).