[Bug libfortran/101310] Bind(C): CFI_section seems confused by pointer arrays

["sandra at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101310

--- Comment #1 from sandra at gcc dot gnu.org ---
Looks like 3 bugs for the price of 1!

First off the loop to fill in the result dimensions in CFI_section seemed to be
applying the base adjustment twice in different ways, or something like that. 
I've rewritten and simplified that code.

The section-3 and section-3p test cases were themselves buggy.  I swear I fixed
one of bugs before but I must have discarded that change along with some failed
experiments/debugging code for the bug above.

Finally, fc-out-descriptor-7 was failing because it uses the same pointer array
as both source and result, and CFI_section was messing with the dimensions in
result before computing the base address adjustment from source.  This ended up
not having anything to do with the result array being intent(out).

I'm going to add some more test cases and regression-test before posting the
patch, but I do have fixes for all 3 bugs now.