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

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

Change-Id: Id1265b5c7c25775eed211ca5035fda5810c6642b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>