fortran tests change

[Craig Burley]

>I propose to move the u77-test.f file from libf2c/U77 to the fortran
>testsuite execute directory with these changes, so that the library
>gets tested properly.  Craig will doubtless spot typos, testing
>notwithstanding.

(I didn't, offhand.)

I like this!  Presumably for the mainline, not 1.1 branch, right?

Would it be useful to maintain a stripped-down original version that
does whatever the new version doesn't, which, offhand, seems to be
only CALL EXIT(1)?  It's reassuring to me to see that "Exit status 1"
or whatever after the pertinent message.

        tq vm, (burley)