Add utilities to aom_dsp for modeling correlated noise.

The auto-regressive model allows for different window shapes
and different lag sizes.

Although most likely to be used as a reference for modeling
noise in AV1, the model is currently parameterized more generally
than AV1 needs.

I will add an example (hopefully with a denoiser) in future
commits.

Change-Id: I1ba1067543601c2c01db4970d42766bb35da77f0
diff --git a/aom_dsp/aom_dsp.cmake b/aom_dsp/aom_dsp.cmake
index f676c40..e21a6d9 100644
--- a/aom_dsp/aom_dsp.cmake
+++ b/aom_dsp/aom_dsp.cmake
@@ -302,6 +302,10 @@
       "${AOM_ROOT}/aom_dsp/bitwriter.h"
       "${AOM_ROOT}/aom_dsp/bitwriter_buffer.c"
       "${AOM_ROOT}/aom_dsp/bitwriter_buffer.h"
+      "${AOM_ROOT}/aom_dsp/noise_util.h"
+      "${AOM_ROOT}/aom_dsp/noise_util.c"
+      "${AOM_ROOT}/aom_dsp/noise_model.c"
+      "${AOM_ROOT}/aom_dsp/noise_model.c"
       "${AOM_ROOT}/aom_dsp/psnr.c"
       "${AOM_ROOT}/aom_dsp/psnr.h"
       "${AOM_ROOT}/aom_dsp/sad.c"