cta/CTA#130 Helgrind gets spurious when using `std::mutex` in the catalogue.

With respect to the rdbms::OcciRset class.  Replaced
std::mutex and std::lock_guard with their helgrind friendly
drop in replacements threading::Mutex and
threading::MutexLocker.

rdbms/OcciRset.cpp

@@ -117,7 +117,7 @@ bool OcciRset::columnIsNull(const std::string &colName) const {
 // close
 //------------------------------------------------------------------------------
 void OcciRset::close() {
-  std::lock_guard<std::mutex> lock(m_mutex);
+  threading::Mutex locker(m_mutex);
 
   if(nullptr != m_rset) {
     m_stmt->closeResultSet(m_rset);
@@ -150,7 +150,7 @@ optional<std::string> OcciRset::columnOptionalString(const std::string &colName)
 //------------------------------------------------------------------------------
 optional<uint64_t> OcciRset::columnOptionalUint64(const std::string &colName) const {
   try {
-    std::lock_guard<std::mutex> lock(m_mutex);
+    threading::Mutex locker(m_mutex);
 
     const int colIdx = m_colNameToIdx.getIdx(colName);
     const std::string stringValue = m_rset->getString(colIdx);

rdbms/OcciRset.hpp

@@ -18,11 +18,11 @@
 
 #pragma once
 
-#include "ColumnNameToIdx.hpp"
-#include "Rset.hpp"
+#include "common/threading/Mutex.hpp"
+#include "rdbms/ColumnNameToIdx.hpp"
+#include "rdbms/Rset.hpp"
 
 #include <memory>
-#include <mutex>
 #include <occi.h>
 
 namespace cta {
@@ -104,7 +104,7 @@ private:
   /**
    * Mutex used to serialize access to this object.
    */
-  mutable std::mutex m_mutex;
+  mutable threading::Mutex m_mutex;
 
   /**
    * The OCCI statement.