Overflow in W_extract_l
# Basic info
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- Fixed point: 7847d456
# Bug description
An overflow has been detected when extracting the lower part of a 64bits word. This is certainly not a desirable. This happen when using the stereo 2, command line (thus the TD part of the stereo) and the down-mixing of that sub-mode is still problematic. So I suggest, to review this issues once #1136 is solved to check if it is still a problem or not

# Ways to reproduce
IVAS_cod -STEREO 2 16400 48.\\ivas-codec\\scripts\\testv\\stvST48c.wav bit16400
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issue