Mac: Remove stderr output from lib preload. This was causing the debug bots to fail. Bug: angleproject:5467 Change-Id: Iea7fe0260e23c1c9770c431d52fea49335b3d0cf Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2593568 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>