zoneinfo: adjust to current timezone data file structure

zoneinfo: adjust to current timezone data file structure

Tweak the package to better match the current file structure in the
upstream time zone database. Add missing aliases. Make some clarifications

* Combine -northmerica and -southamerica into -america, as all
  current official America/xxx definitions were already in -northamerica
  and only the unofficial/deprecated Brazil/xxx, Chile and Argentina were
  in -southamerica. (Confusingly America/Sao_Paulo was in northamerica,
  while Brazil was in southamerica.)
  * Add PROVIDES for the old package names

* Add missing top-level dir country/nation alias links.
* Define Eire in -europe instead of -core.

* Rename -india to -indian, as it contains the Indian ocean islands
  instead of the actual Asia/Kolkata zone for the mainland India.
  * Add PROVIDES for the old package name

* Add 'Ocean' to all ocean zone titles.

* Make all zoneinfo-packages depend on zoneinfo-core, so that zone.tab,
  the UTC based definitions and the still existing short zone codes are
  always available.

* Clarify menuconfig menu as "Time Zone info"

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>