makefile entry xml-validate-local

Makefile.in

@@ -449,6 +449,11 @@ xml-validate:
 	  xmllint --noout --valid $$x 2>&1 | head -1; \
 	done
 
+xml-validate-local:
+	@for x in `find examples/ -name why3session.xml`; do \
+	  xmllint --noout --dtdvalid share/why3session.dtd $$x 2>&1 | head -1; \
+	done
+
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 # Config
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