Removing definition of _CRT_SECURE_NO_WARNINGS.
Removing definition of _CRT_SECURE_NO_WARNINGS.

WebRTC code compiles with //build/config/compiler:chromium_code, which
adds "/wd4996" and makes _CRT_SECURE_NO_WARNINGS redundant.

Bug: None
Change-Id: If033e7c60cc1a640db77d075aab07b2562740d4a
Reviewed-on: https://webrtc-review.googlesource.com/72001
Reviewed-by: Patrik Höglund <b486136ee68458b09c92c86c39f451c87d6ef6a1@webrtc.org>
Commit-Queue: Mirko Bonadei <d2c43c210eae6feef04f53bae50885e8152edcca@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#22991}
ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc