recent versions of linux have dropped the hayes esp driver

http://bugs.gentoo.org/309883

--- a/setserial.c
+++ b/setserial.c
@@ -21,6 +21,8 @@
 #endif
 #ifdef HAVE_LINUX_HAYESESP_H
 #include <linux/hayesesp.h>
+#else
+#undef TIOCGHAYESESP
 #endif
 #include <linux/serial.h>