Delete unneeded includes of atomic32.h.

BUG=None

Review-Url: https://codereview.webrtc.org/3002173002
Cr-Original-Commit-Position: refs/heads/master@{#19484}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 821e21402d84373f790d106c1f017cd9adb8ce3d
2 files changed