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

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

rdbms/SqliteStmt.cpp

@@ -118,7 +118,7 @@ SqliteStmt::~SqliteStmt() throw() {
 // close
 //------------------------------------------------------------------------------
 void SqliteStmt::close() {
-  std::lock_guard<std::mutex> lock(m_mutex);
+  threading::MutexLocker locker(m_mutex);
 
   if(nullptr != m_stmt) {
     sqlite3_finalize(m_stmt);

rdbms/SqliteStmt.hpp

@@ -18,11 +18,11 @@
 
 #pragma once
 
+#include "common/threading/Mutex.hpp"
 #include "rdbms/Stmt.hpp"
 
 #include <map>
 #include <memory>
-#include <mutex>
 #include <stdint.h>
 #include <sqlite3.h>
 
@@ -136,7 +136,7 @@ private:
   /**
    * Mutex used to serialize access to the prepared statement.
    */
-  std::mutex m_mutex;
+  threading::Mutex m_mutex;
 
   /**
    * The SQL connection.