[releng] Make Ecore Tools installation optional in the setup.
diff --git a/plugins/org.eclipse.xsd/XSD.setup b/plugins/org.eclipse.xsd/XSD.setup
index 47bf4e3..ac1a7e4 100644
--- a/plugins/org.eclipse.xsd/XSD.setup
+++ b/plugins/org.eclipse.xsd/XSD.setup
@@ -94,7 +94,8 @@
         name="org.eclipse.emf.sdk.feature.group"/>
     <requirement
         name="org.eclipse.emf.ecoretools.sdk.feature.group"
-        versionRange="(0.0.1,3.0.0)"/>
+        versionRange="(0.0.1,3.0.0)"
+        optional="true"/>
     <requirement
         name="org.eclipse.xsd.sdk.feature.group"/>
     <repository