[Cmake] cmAddTestCommand breaks

[Amitha Perera]

In cmAddTestCommand.cxx:82, there is
     std::ios_base::app
which is the correct, standards-compliant way of specifing the append
mode. Unfortunately, with gcc 2.95.2 (under FreeBSD at least), this
fails. std::ios::app works, though.

What can and should be done to fix this?

Thanks,
Amitha.