Synchronize thread output to the test checksum report stream.

Test/Checksum.cc

@@ -6,6 +6,7 @@
 #include "Base/Debug/DebCallStack.hh"
 #include <fstream>
 #include <iostream>
+#include <mutex>
 
 namespace Test {
 namespace Checksum {
@@ -137,20 +138,24 @@ Difference Object::compare(
 
 void Object::add(const Result& _rslt, const String& _data)
 {
+  static std::mutex mtx; //synchronize access to the checksum report stream
+  std::lock_guard<std::mutex> lock(mtx);
+
   static Base::OutputStreamAdaptT<std::ofstream> test_str(REPORT_FILENAME);
   static bool tag_out = false;
 
 #ifdef DEB_ON
   static String prev_call_stck;
-
   String call_stck("/");
   Debug::CallStack::query().append(call_stck);
+
   if (prev_call_stck != call_stck)
   {
     test_str << call_stck << Base::LF;
     prev_call_stck = call_stck;
   }
 #endif//DEB_ON
+
   if (!tag_out)
   {
     tag_out = true;