Audio: Use std::deque instead of std::vector for the audio buffer type (StereoBuffer16).

The current code inserts and deletes elements from the beginning of the audio buffer, which is very inefficient in an std::vector.

Profiling was done using VisualStudio2017's Performance Analyzer in Super Mario 3D Land.

Before this change: AudioInterp::Linear had 14.14% of the runtime (inclusive) and most of that time was spent in std::vector's insert implementation.
After this change: AudioInterp::Linear has 0.36% of the runtime (inclusive)

src/audio_core/interpolate.cpp

@@ -47,7 +47,7 @@ static void StepOverSamples(State& state, StereoBuffer16& input, float rate,
     state.xn1 = input[inputi + 1];
     state.fposition = fposition - inputi * scale_factor;
 
-    input.erase(input.begin(), input.begin() + inputi + 2);
+    input.erase(input.begin(), std::next(input.begin(), inputi + 2));
 }
 
 void None(State& state, StereoBuffer16& input, float rate, DSP::HLE::StereoFrame16& output,