Merge commit 'refs/top-bases/gcc-unused' into gcc-unused

diff --cc module/zfs/dbuf.c
Simple merge

diff --cc module/zfs/dnode.c
Simple merge

diff --cc module/zfs/dnode_sync.c
Simple merge

diff --cc module/zfs/dsl_dataset.c
Simple merge

diff --cc module/zfs/dsl_dir.c
Simple merge

diff --cc module/zfs/vdev.c
Simple merge

diff --cc module/zfs/vdev_cache.c
Simple merge