Update to current rust: use the new attributes syntax.
Update to current rust: use the new attributes syntax.

klutzy/rust-harfbuzz,klutzy/rust-harfbuzz,ruud-v-a/rust-harfbuzz,ruud-v-a/rust-harfbuzz,klutzy/rust-harfbuzz,klutzy/rust-harfbuzz,ruud-v-a/rust-harfbuzz,ruud-v-a/rust-harfbuzz,klutzy/rust-harfbuzz,ruud-v-a/rust-harfbuzz