Remove xz_chromeos.cc am: e68e13045e

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/3304584

Change-Id: Ifdccc78c353b40b675f844038b19d901590ff511
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>