Non-allocated arrays accessed in output

[micaeljtoliveira]

As discussed in #410, there are a few places where non-allocated arrays are accessed in src/offline/cable_output.F90. Nothing is really done with the arrays and the code works fine with the Intel compiler, but gfortran produces a segmentation fault.

The proposed solution is to fence the affected code to make sure arrays are only accessed if they were allocated.

As a side-note, the code would probably be more robust (i.e, compilers would better identify and report the issue) if the arrays were declared as allocatables instead of pointers. This would also probably generate faster code.