As an XML file:

http://unicode.org/repos/cldr/trunk/common/supplemental/windowsZones.xml

As a C .h file:

https://github.com/mirror/newlib-cygwin/blob/master/winsup/utils/tzmap.h

As a shell script to convert the first to the second

https://github.com/mirror/newlib-cygwin/blob/master/winsup/utils/tzmap-from-unicode.org

We'll need this information later, probably.