Get rid of some unnecessary commented out code (issue #6849)

There is a lot of false positives (see [attached logs](http://code.google.com/p/sympy/issues/detail?id=3750#c1)), so I don't think that we should automate such cleanup.

fixes #6849
Thanks, KO)  I mean, what exactly do you suggest to achieve this goal.  E.g. add some compatibility lib for Fortran, which will implement such function.

If you don't know how exactly something should be implemented - IMHO you shouldn't use comments in the codebase, but our bugtracker instead.