Serialize built-ins on 'ant dist'

Don't store binary data in the repository anymore. From now on any test on the
compiler requires that 'ant dist' was executed at least once since the last
update of the built-ins

core/descriptors/descriptors.iml

@@ -10,6 +10,7 @@
     <orderEntry type="library" scope="PROVIDED" name="intellij-core" level="project" />
     <orderEntry type="module" module-name="util.runtime" />
     <orderEntry type="module" module-name="serialization" />
+    <orderEntry type="library" exported="" name="builtins" level="project" />
   </component>
 </module>