Added FreeBSD support

tty/Terminal_bsd.go

@@ -0,0 +1,11 @@
+//go:build darwin || freebsd
+
+package tty
+
+import "golang.org/x/sys/unix"
+
+// IsTerminal returns true if the file descriptor is a terminal.
+func IsTerminal(fd uintptr) bool {
+	_, err := unix.IoctlGetTermios(int(fd), unix.TIOCGETA)
+	return err == nil
+}