Remove C++11 calls from intelligibility_utils

webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc

Index: webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc
diff --git a/webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc b/webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc
index d67d200689f1613391c18c138b55f504a18ffde4..730bb976e1fddacb153690b98e74d563ad84d050 100644
--- a/webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc
+++ b/webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc
@@ -31,14 +31,6 @@ float UpdateFactor(float target, float current, float limit) {
   return current + sign * fminf(delta, limit);
 }
 
-bool cplxfinite(complex<float> c) {
-  return std::isfinite(c.real()) && std::isfinite(c.imag());
-}
-
-bool cplxnormal(complex<float> c) {
-  return std::isnormal(c.real()) && std::isnormal(c.imag());
-}
-
 complex<float> zerofudge(complex<float> c) {
   const static complex<float> fudge[7] = {{0.001f, 0.002f},
                                           {0.008f, 0.001f},
@@ -48,7 +40,7 @@ complex<float> zerofudge(complex<float> c) {
                                           {0.003f, 0.004f},
                                           {0.002f, 0.009f}};
   static int fudge_index = 0;

[Andrew MacDonald, 2015/07/22 22:17:07]

Ahh, non-const static!

Do we really need this zerofudge thing at all? There's a comment here:
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/webrtc...

that says "Can probably be removed."

[ekm, 2015/07/22 22:45:25]

I think that's saying the |skip_fudge| flag can be removed. zerofudge does catch
some div by 0 errors in other places (e.g.,
IntelligibilityEnhancer::SolverForGainsGivenLambda). There's surely a better way
to deal with this, but we need to do something. I've changed it to use rand().

[Andrew MacDonald, 2015/07/22 23:34:59]

Got it. Is there any benefit to adding this dither, or can we just ensure the
components never fall below some small value? Something like this:

float ClampToMinAbs(float value, float min_abs_value) {
  return std::abs(value) < min_abs_value ? min_abs_value : value;
}

complex<float> ZeroFudge(complex<float> c) {
  const float kMinValue = 0.001f;
  return complex<float>(ClampToMinAbs(c.real(), kMinValue),
ClampToMinAbs(c.imag(), kMinValue));
}

[ekm, 2015/07/23 00:06:26]

That's a good question. I think we want the dither, otherwise we could still end
up with 0 variance if all samples are equal.

-  if (cplxfinite(c) && !cplxnormal(c)) {
+  if (c.real() == 0.f || c.imag() == 0.f) {
     fudge_index = (fudge_index + 1) % 7;
     return c + fudge[fudge_index];
   }