Upgrade libtracefs to libtracefs-1.8.1 am: b6c97c53a6

Original change: https://android-review.googlesource.com/c/platform/external/libtracefs/+/3470320

Change-Id: I0f388d417cac314e64eb34b232582e78d8eef2c9
Signed-off-by: Automerger Merge Worker <[email protected]>