Expose I_ constants. Auto-detect stropts.h. Properly configure the slave terminal.
diff --git a/pyconfig.h.in b/pyconfig.h.in
index 56a5c75..eba68f6 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -439,6 +439,9 @@
 /* Define to 1 if you have the <string.h> header file. */
 #undef HAVE_STRING_H
 
+/* Define to 1 if you have the <stropts.h> header file. */
+#undef HAVE_STROPTS_H
+
 /* Define to 1 if you have the `strptime' function. */
 #undef HAVE_STRPTIME