gfortran.dg testsuite

[Tobias Schlüter]

FYI I have setup a gfortran.dg testsuite so that we can test compiler 
output. I plan to use this to scan for error messages, as I have a fixes 
waiting for my copyright assignment which deal with superfluous 
warnings. Is this the right thing to do, or were there other plans?

This was surprisingly easy, and involved only changing g77 to gfortran 
in a few places + adding a few lines so that tests ending in .f90 are 
run. Paul, do you think that is copyrightable? If not I'll post a patch.

- Tobi