[flang-commits] [flang] [flang] Fix ISO_Fortran_binding.h to work better with C++ code (PR #82556)

[Pete Steinfeld via flang-commits]

psteinfeld wrote:

In separate testing (see PR #82811), I convinced my selv that the failing Windows build of these changes has nothing to do with the changes themselves.

https://github.com/llvm/llvm-project/pull/82556