Add DEC Ultrix notes (from Donn Cave's email).
diff --git a/README b/README
index eacc4ee..3e0c6e9 100644
--- a/README
+++ b/README
@@ -203,6 +203,9 @@
reported for GCC 2.7.2.3 on selectmodule.c. Manually compile
the affected file without optimization to solve the problem.
+DEC Ultrix: compile with GCC to avoid bugs in the native compiler,
+ and pass SHELL=/bin/sh5 to Make when installing.
+
AIX: A complete overhaul of the shared library support is now in
place. See Misc/AIX-NOTES for some notes on how it's done.
(The optimizer bug reported at this place in previous releases