Fix some compiler warnings

Author: kamahen

libcds/include/RMQ_succinct.h

@@ -55,7 +55,7 @@ namespace cds_static
 			void  save(ostream & fp);
 			RMQ_succinct * load(istream & fp);
 
-			~RMQ_succinct();
+			virtual ~RMQ_succinct();
 
 		protected:
 			/* size of array a*/

libcds/include/TextIndexCSA.h

@@ -49,7 +49,7 @@ namespace cds_static
 			 **/
 			TextIndexCSA(uchar *text, ulong length, char *build_options);
 
-			~TextIndexCSA();
+			virtual ~TextIndexCSA();
 
 			/* Writes in numocc the number of occurrences of the substring
 			 * pattern[0..length-1] found in the text indexed by index. */

libcds/src/static/bitsequence/BitSequenceRRR.cpp

@@ -422,7 +422,7 @@ namespace cds_static
 			ret->create_sampling(ret->sample_rate);
 			return ret;
 		}
-		catch(exception e) {
+		catch(const exception&) {
 			delete ret;
 		}
 		return NULL;

libhdt/src/rdf/RDFParser.cpp

@@ -24,6 +24,7 @@ RDFParserCallback *RDFParserCallback::getParserCallback(RDFNotation notation) {
 #else
 		throw ParseException("No Parser available for input RDF Format");
 #endif
+    return nullptr;
 }
 
 }

libhdt/tools/hdtSearch.cpp

@@ -98,7 +98,7 @@ void iterate(HDT *hdt, char *query, ostream &out, bool measure, uint32_t offset)
                 it->skip(offset);
                 offset = 0;
             }
-            catch (const runtime_error error) {
+            catch (const runtime_error&) {
                 /*invalid offset*/
                 interruptSignal = 1;
             }