fix one c++ UB in corpus2_whole

libcorpus2_whole/io/corpusreader.cpp

@@ -30,6 +30,10 @@ CorpusReader::CorpusReader(const Tagset& tagset, const std::string& corpus_type)
 	//
 }
 
+CorpusReader::~CorpusReader()
+{
+}
+
 boost::shared_ptr<Corpus> CorpusReader::read(const std::string& corpus_file_path)
 {
 	try {

libcorpus2_whole/io/corpusreader.h

@@ -36,6 +36,8 @@ public:
 	 */
 	CorpusReader(const Tagset& tagset, const std::string& corpus_type);
 
+	virtual ~CorpusReader();	
+
 	/**
 	 * Reads corpus from given path
 	 * @arg corpus_file Path to file contains paths to corpus files.