Support Library Libiconv

The support library libiconv will (by default) be built in version 1.15, as controllable by the CMake cache variables LIBICONV_VERSION, LIBICONV_URL and LIBICONV_HASH.

Dependencies

Libiconv does not depend on any of the other support libraries. It depends on CYGWIN_BASH and the custom shell script windres-rc.sh for adapting arguments in Windres convention to Visual Studio’s RC.EXE.