Add tools::on_startup, and warn about glibc 2.25 bug if found

https://sourceware.org/bugzilla/show_bug.cgi?id=21778

src/common/util.h

@@ -129,6 +129,8 @@ namespace tools
 
   bool sanitize_locale();
 
+  bool on_startup();
+
   /*! \brief Defines a signal handler for win32 and *nix
    */
   class signal_handler