[flang][OpenMP] move omp end directive validation to semantics (#154739)

The old parse tree errors quckly exploded to thousands of unhelpful
lines when there were multiple missing end directives (e.g. #90452).

Instead I've added a flag to the parse tree indicating when a missing
end directive needs to be diagnosed, and moved the error messages to
semantics (where they are a lot easier to control).

This has the disadvantage of not displaying the error if there were
other parse errors, but there is a precedent for this approach (e.g.
parsing atomic constructs).

0 files changed, 0 insertions, 0 deletions