Add output entries to build.properties in o.e.help.base

This should fix the build.

See: eclipse-tycho/tycho#3019

ua/org.eclipse.help.base/build.properties

@@ -14,6 +14,7 @@
 source..=src/,\
          src_demo/
 src.includes=schema/,about.html
+output.. = bin/
 bin.includes = doc/,\
                plugin.xml,\
                preferences.ini,\
@@ -30,5 +31,6 @@ bin.includes = doc/,\
 jars.compile.order = .,\
                      ant_tasks/helpbase-ant.jar
 source.ant_tasks/helpbase-ant.jar = src_ant/
+output.ant_tasks/helpbase-ant.jar = bin2/
 jars.extra.classpath = platform:/plugin/org.apache.ant/lib/ant.jar
 javacWarnings..=-unchecked,raw