spgram: adding check for stand-alone operation
spgram: adding check for stand-alone operation

JayKickliter/liquid-dsp,jgaeddert/liquid-dsp,wangning223/liquid-dsp,wangning223/liquid-dsp,JayKickliter/liquid-dsp,jgaeddert/liquid-dsp,wangning223/liquid-dsp,JayKickliter/liquid-dsp,jgaeddert/liquid-dsp,JayKickliter/liquid-dsp,jgaeddert/liquid-dsp,jgaeddert/liquid-dsp,wangning223/liquid-dsp,wangning223/liquid-dsp,JayKickliter/liquid-dsp