Use the real glibc openpty if present.
diff --git a/include/config.h.in b/include/config.h.in
index d154872..056dff3 100644
--- a/include/config.h.in
+++ b/include/config.h.in
@@ -182,6 +182,9 @@
/* Define if you have the memmove function. */
#undef HAVE_MEMMOVE
+/* Define if you have the openpty function. */
+#undef HAVE_OPENPTY
+
/* Define if you have the rfork function. */
#undef HAVE_RFORK
@@ -305,6 +308,9 @@
/* Define if you have the <netinet/tcp.h> header file. */
#undef HAVE_NETINET_TCP_H
+/* Define if you have the <pty.h> header file. */
+#undef HAVE_PTY_H
+
/* Define if you have the <resolv.h> header file. */
#undef HAVE_RESOLV_H