[javalib] fixed annotation 'element_value' structure parsing (http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.7.16.1)


git-svn-id: http://ocamllibs.googlecode.com/svn/trunk@277 21970f9d-2756-cbab-44b1-85fcaa48d7c2