iconvctl(3) on macOS

The text f3f2b875c497, as macOS 15.1, macOS 15.0, macOS 14.6, macOS 14.5, macOS 14.4, macOS 14.3, macOS 14.2, macOS 14.1, macOS 14.0 shipped it.

controlling and diagnostical facility for iconv(3)