if (error_hook) (*error_hook) ();
if (deprecated_error_hook) (*deprecated_error_hook) ();
gdb_os_error (host_callback * p, const char *format,...){  if (error_hook)    (*error_hook) ();  else    {      va_list args;      va_start (args, format);      verror (format, args);      va_end (args);    }}