Andy Dustman: add GNU pth user-space thread support.
diff --git a/config.h.in b/config.h.in
index 9703558..ce254b8 100644
--- a/config.h.in
+++ b/config.h.in
@@ -103,6 +103,9 @@
    This is the case on Motorola V4 (R40V4.2) */
 #undef GETTIMEOFDAY_NO_TZ
 
+/* Define if you have GNU PTH threads */
+#undef _GNU_PTH
+
 /* Define this if your time.h defines altzone */
 #undef HAVE_ALTZONE