Prevent the generation of empty <itemizedlist> elements, which is invalid

docbook and causes apache fop 0.94 to choke and die.



[SVN r40047]

tools/boostbook

@@ -1 +1 @@
-Subproject commit 9b2ca02ca1f6dbc0ccfc42fb344df6bd8849ce50
+Subproject commit caeaebade43599f91ecaa2f32e5454144487f54c