0.2.188

Changed

• Restore Send and Sync for DIR (35b062263401)

These were removed in 0.2.187 because libc does not actually make Send and Sync
guarantees about DIR (or other extern types), but this caused some crates to break.
The traits are added back for now to allow time to migrate, but will be removed again
in the future; please make sure your crates are not relying on libc::DIR: Send or
libc::DIR: Sync.