ENH: Require language libs in Fortran/C test

This extends the Fortran/C interface test to require that the executable
link to the fortran language runtime libraries.  We must verify that the
proper linker is chosen.

Tests/Fortran/mysub.f

@@ -1,4 +1,5 @@
       subroutine mysub
+        print *, 'Printing this requires fortran language libraries'
       end subroutine
       subroutine my_sub
       end subroutine