fft|benchmark: adding benchmarks for all real DFTs (e.g. DCT/DST)
fft|benchmark: adding benchmarks for all real DFTs (e.g. DCT/DST)

manuts/liquid-dsp,cjcliffe/liquid-dsp,jgaeddert/liquid-dsp,wangning223/liquid-dsp,manuts/liquid-dsp,manuts/liquid-dsp,JayKickliter/liquid-dsp,jgaeddert/liquid-dsp,JayKickliter/liquid-dsp,wangning223/liquid-dsp,biotrump/liquid-dsp,cjcliffe/liquid-dsp,jgaeddert/liquid-dsp,andrepuschmann/liquid-dsp,andrepuschmann/liquid-dsp,andrepuschmann/liquid-dsp,JayKickliter/liquid-dsp,biotrump/liquid-dsp,manuts/liquid-dsp,jgaeddert/liquid-dsp,andrepuschmann/liquid-dsp,biotrump/liquid-dsp,cjcliffe/liquid-dsp,wangning223/liquid-dsp,wangning223/liquid-dsp,jgaeddert/liquid-dsp,cjcliffe/liquid-dsp,biotrump/liquid-dsp,JayKickliter/liquid-dsp,wangning223/liquid-dsp,cjcliffe/liquid-dsp,JayKickliter/liquid-dsp,biotrump/liquid-dsp,andrepuschmann/liquid-dsp,manuts/liquid-dsp