Fixed some memleaks

arangod/Indexes/HashIndex.cpp

@@ -656,6 +656,7 @@ int HashIndex::removeMultiElement(TRI_index_element_t* element, bool isRollback)
         return TRI_ERROR_INTERNAL;
       }
     }
+    TRI_index_element_t::free(old);
     return TRI_ERROR_NO_ERROR;
 }
 

arangod/Indexes/SkiplistIndex2.cpp

@@ -237,6 +237,7 @@ int SkiplistIndex2::remove (TRI_doc_mptr_t const* doc,
   size_t count = elements.size();
   for (size_t i = 0; i < count; ++i) {
     res = _skiplistIndex->skiplist->remove(elements[i]);
+    TRI_index_element_t::free(elements[i]);
   }
   return res;
 }