Fixed buffer overrun by using vsnprintf instead of vsprintf

Common/System/vtkTimerLog.cxx

@@ -124,7 +124,7 @@ void vtkTimerLog::FormatAndMarkEvent(const char *format, ...)
   static  char event[4096];
   va_list var_args;
   va_start(var_args, format);
-  vsprintf(event, format, var_args);
+  vsnprintf(event, sizeof(event), format, var_args);
   va_end(var_args);
 
   vtkTimerLog::MarkEventInternal(event, vtkTimerLogEntry::STANDALONE);

Common/System/vtkTimerLog.h

@@ -109,7 +109,7 @@ public:
 
   /**
    * Record a timing event.  The event is represented by a formatted
-   * string.
+   * string.  The internal buffer is 4096 bytes and will truncate anything longer.
    */
 #ifndef __VTK_WRAP__
   static void FormatAndMarkEvent(const char *EventString, ...) VTK_FORMAT_PRINTF(1, 2);