add gfortran debug stage to firebot to catch unused variables

[gforney]

Despite using -warn unused in the _db compile flags, Intel does not catch these unused variables if they are within a subroutine that is "CONTAINED" within another.

But, gfortran does catch these. Add a gfortran _db compile stage to firebot and report any unused warnings.

[rmcdermo]

Yep. I see it.

[gforney]

implemented now in both firebot and smokebot