Label /system/usr/share/zoneinfo differently

/system/usr/share/zoneinfo is currently labeled zoneinfo_data_file,
a label shared with /data/misc/zoneinfo. However, each of these
directory locations has different security characteristics. In
particular, the files in /system/usr/share/zoneinfo must never be
writable, whereas /data/misc/zoneinfo may be written to by system_server.
Reusing the same label hides these different security characteristics.

Create a separate label for /system/usr/share/zoneinfo.

Test: Device boots and no obvious problems.
Change-Id: I8cf16ff038b06b38f77388e546d9b7a6865f7879