Add MSan annotation for system.stack_trace

src/Common/StackTrace.cpp

@@ -261,6 +261,9 @@ StackTrace::StackTrace(const ucontext_t & signal_context)
 {
     tryCapture();
 
+    /// This variable from signal handler is not instrumented by Memory Sanitizer.
+    __msan_unpoison(&signal_context, sizeof(signal_context));
+
     void * caller_address = getCallerAddress(signal_context);
 
     if (size == 0 && caller_address)