+ close cleanly the writabledatabse at the end of the indexing process

src/common/kiwix/xapianIndexer.cpp

@@ -92,7 +92,8 @@ namespace kiwix {
   void XapianIndexer::indexingPostlude() {
     this->flush();
     this->writableDatabase.commit_transaction();
-    
+    this->writableDatabase.close();
+
     // commit is not available is old version of xapian and seems not mandatory there
     // this->writableDatabase.commit();
   }