Test: run test on a WAVE file with WAVE_FORMAT_EXTENSIBLE flag

[cchampet]

EBU file: seq-3341-6-6channels-WAVEEX-16bit.wav
https://github.com/mikrosimage/loudness_validator/blob/develop/test/loudness-analyser.cpp#L156

[MarcAntoine-Arnaud]

Requires to support 5.1 audio channel layout (LFE is the 4th channel, not the last one)

[cchampet]

Indeed, checkout the following doc:
http://people.bath.ac.uk/masrwd/ncdream/researchdev/wave-ex/wave_ex.html