Remove $FZF_LISTEN_PORT

It is not worth the added complexity.

man/man1/fzf.1

@@ -732,8 +732,6 @@ e.g.
      # Send action to the server
      curl -XPOST localhost:6266 -d 'reload(seq 100)+change-prompt(hundred> )'
      \fR
-
-The port number is exported as \fB$FZF_LISTEN_PORT\fR on the child processes.
 .TP
 .B "--version"
 Display version information and exit

src/terminal.go

@@ -2267,9 +2267,6 @@ func (t *Terminal) Loop() {
 						env = append(env, "FZF_PREVIEW_"+lines)
 						env = append(env, columns)
 						env = append(env, "FZF_PREVIEW_"+columns)
-						if t.listenPort > 0 {
-							env = append(env, fmt.Sprintf("FZF_LISTEN_PORT=%d", t.listenPort))
-						}
 						cmd.Env = env
 					}