packetizer's realloc() method now accepts NULL pointer
packetizer's realloc() method now accepts NULL pointer

  * allowing NULL pointer to be passed as first argument
  * acts more like realloc() function in standard library

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