Fix EP generation event output format for uint. This should be %u not %d. BUG=angleproject:1309 Change-Id: I1fe1b8df9ea4f9123fc05e9ff58afa1f7723692c Reviewed-on: https://chromium-review.googlesource.com/636521 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>