[Flang][OpenMP] Update semantics checks for 'teams' nesting (#126922)
This patch introduces a directive set for combined constructs where
`teams` is the last leaf. This is used in a couple places to simplify
checks, which is NFC, but it also replaces two incorrect uses of
`topTeamsSet`.
Before, these checks would incorrectly skip combined constructs where
`teams` was the last leaf construct when checking for allowed nested
constructs inside of a `teams` region. Similarly, it would also
incorrectly perform these checks whenever a compound `teams` construct
where `teams` was the first leaf construct was found.
llvm-project
f13aea1d - [Flang][OpenMP] Update semantics checks for 'teams' nesting (#126922)
