libssh2_channel_setenv(3) on Linux
The text fc8773714c44, as Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie), Debian 7 (Wheezy) shipped it.
convenience macro for libssh2_channel_setenv_ex(3) calls