[flang] [llvm] [flang][OpenMP] Decompose compound constructs, do recursive lowering (PR #90098)

[Krzysztof Parzyszek via llvm-commits]

kparzysz wrote:

> ```
> parallel-sections.f90
> ```
This test uses `allocate` clause without a privatizing clause.  The failure is of the same type to the one in "taskgroup.f90".  One way to fix this is to add `private(x, y)` to the construct.  This would cause the `allocate` to only apply to `sections` (since that's where the `private` clause would apply).  https://github.com/llvm/llvm-project/pull/92185

https://github.com/llvm/llvm-project/pull/90098