Fixes ArrayIndexOutOfBoundsException at Facet.computeMultivalued

java.lang.ArrayIndexOutOfBoundsException: 11
	at org.apache.lucene.util.OpenBitSet.fastGet(OpenBitSet.java:184)
	at com.jaeksoft.searchlib.facet.Facet.computeMultivalued(Facet.java:164)
	at com.jaeksoft.searchlib.facet.Facet.facetMultivalued(Facet.java:134)