Log Message:
Updated libzip to 1.2.0.

1.2.0 [2017-02-19]
==================

* Support for AES encryption (Winzip version), both encryption
  and decryption.
* Support legacy zip files with >64k entries.
* Fix seeking in zip_source_file if start > 0.
* Add zip_fseek() for seeking in uncompressed data.
* Add zip_ftell() for telling position in uncompressed data.
* Add zip_register_progress_callback() for UI updates during zip_close()