Merge "Stop using -Wno-unused-variable" am: 8a73bf6710 am: e3a45f74b9 am: 8272eb8819

Original change: https://android-review.googlesource.com/c/platform/system/vold/+/2021315

Change-Id: I4934bde520993558d4f98fc81861f89647cd14fd