New test for generic Makefile.pre.in
diff --git a/Demo/extend/README b/Demo/extend/README
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+This directory contains a test and demonstration of the power of the
+generic Makefile.pre.in from the Misc directory. There are three
+shell scripts. Study the source of the scripts to find out how they
+work (it's really easy).
+
+./make_static Make a static python binary with the xx module
+ linked in. To test this, run ./python and try to
+ import xx.
+
+./make_shared Make a shared module xx. To test this, run the
+ standard python interpreter in this directory and try
+ to import xx.
+
+./make_clean Clean up after either of the above. Note that each
+ scripts starts by calling this script, to begin with a
+ clean slate.