Re-enable LTO for linux-kselftest am: 5d9d3fcd36

Original change: https://android-review.googlesource.com/c/platform/external/linux-kselftest/+/2853675

Change-Id: I9401d4461401061c8f6e4b8f1984eb779dba4387
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>