[configure.ac includes.h] add <sys/ptms.h> for grantpt() and friends.
diff --git a/includes.h b/includes.h
index 764bd57..d2cc882 100644
--- a/includes.h
+++ b/includes.h
@@ -134,6 +134,9 @@
 #ifdef HAVE_SYS_STRTIO_H
 #include <sys/strtio.h>	/* for TIOCCBRK on HP-UX */
 #endif
+#if defined(HAVE_SYS_PTMS_H) && defined(HAVE_DEV_PTMX)
+#include <sys/ptms.h>	/* for grantpt() and friends */
+#endif
 
 #include <netinet/in_systm.h> /* For typedefs */
 #include <netinet/in.h> /* For IPv6 macros */