Removing -Wno-strict-overflow from main BUILD.gn.
Removing -Wno-strict-overflow from main BUILD.gn.

Bug: None
Change-Id: I5a3fc30e8dd8f58ab8a3c8a395e51d68de3c28eb
Reviewed-on: https://webrtc-review.googlesource.com/64989
Reviewed-by: Karl Wiberg <2c708eb0a58047bf403399f50b3da33ffd2dd444@webrtc.org>
Commit-Queue: Mirko Bonadei <d2c43c210eae6feef04f53bae50885e8152edcca@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#22645}
TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc