[flang] [llvm] [flang][runtime] Replace recursion with iterative work queue (WORK IN PROGRESS) (PR #137727)

[Peter Klausler via llvm-commits]

klausler wrote:

I've debugged and fixed all of the failures of the work queue implementation exposed by the GNU Fortran test suite and a proprietary one.  Please review when convenient.

https://github.com/llvm/llvm-project/pull/137727