[llvm] [flang][runtime] Refine state associated with child I/O (PR #150461)

[Peter Klausler via llvm-commits]

klausler wrote:

Thanks for that.  I'm not seeing it here with valgrind myself, using a flang-rt build with gcc 9.3.0 for x86-64.  What are you building with?  (It might be a red herring.)

https://github.com/llvm/llvm-project/pull/150461