Sync zoneinfo database with tzdata2018b from ftp://ftp.iana.org/tz/releases

Sync zoneinfo database with tzdata2018b from ftp://ftp.iana.org/tz/releases

* Sao Tome and Principe switched from +00 to +01.

* Brazil's DST will now start on November's first Sunday.

* A discrepancy of 4 s in timestamps before 1931 in South Sudan has
    been corrected.

* The abbreviation invented for Bolivia Summer Time (1931-2) is now
    BST instead of BOST.

* Various smaller adjustments.

For a detailed list of changes, see share/zoneinfo/NEWS.