`OmpStructureChecker` is supposed to work only with `parser::OmpClause`
after tablegen changes for OpenMP and OpenACC were introduced.
Hence `OmpMemoryOrderClause`, `OmpAtomicMemoryOrderClause` and similar ones were failing
to catch semantic errors, inspite of having code for semantic checks.
This patch tries to change parser for `OmpMemoryOrderClause` and similar dependent ones
and use `OmpClauseList` which resides/comes from common tablegen for OpenMP/OpenACC eventually using `parser::OmpClause`.
This patch also tries to :
1. Change `OmpCriticalDirective` in `openmp-parsers.cpp` to support `OmpClauseList`.
2. Check-flang regresses when changes were introduced due to missing semantic checks in OmpCritical, patch implements them at the minimal level to pass the regression.
3. Change tablegen to support Hint clause.
4. Adds missing source locations `CharBlock Source` in each atomic construct.
5. Remove dead code realted to `memory-order-clauses` after moving to `OmpClauseList`.
Reviewed By: kiranchandramohan
Differential Revision: https://reviews.llvm.org/D88965
sameeran joshi