Auto-detect hstrerror. Raise socket.herror in PyH_Error. Register the three
exception classes in the module dictionary.
diff --git a/pyconfig.h.in b/pyconfig.h.in
index e1013fe..4f46a09 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -410,6 +410,9 @@
 /* Define if you have the getwd function.  */
 #undef HAVE_GETWD
 
+/* Define if you have the hstrerror function.  */
+#undef HAVE_HSTRERROR
+
 /* Define if you have the hypot function.  */
 #undef HAVE_HYPOT