If the '--socket-name' argument is unspecified, the environment
variable 'EMACS_SOCKET_NAME' is now consulted with the same
semantics. This mirrors the behavior of the '--server-file' argument,
and allows for easier configuration of emacsclient when the socket is
in a location other than 'TMPDIR' or '/tmp'.
* emacsclient.c (set_socket): Add support for the
EMACS_SOCKET_NAME environment variable. (Bug#33095)