-Changed the type for the frequency estimate of the comfort noise for the
higher band to be a two dimensional float array instead of a complex_t array.
This makes sense since all the other frequency estimate (apart from the
coherence) use this format and doing this change allows bundling the
IFFT operations into using the InverseFFT method.
-Moved the memset of the frequency estimate of the comfort noise to where it is used and made it conditional so that it is only performed when used.
-Harmonized the if-statements for when the frequency estimate of the comfort noise is computed in the different optimized ComfortNoise computation methods.
The changes have been tested for bitexactness.
BUG=webrtc:5201
Review URL: https://codereview.webrtc.org/1494133002
Cr-Commit-Position: refs/heads/master@{#11050}
99b1a32146