Validity check introduce in D90241 are a bit too restrict and this patch propose to losen
them a bit. The duplicate clauses is now check only between the three allowed lists and between the
requiredClauses and allowedClauses lists. This allows to enable some check where a clause can be
required but also appear only once on the directive. We found these kind of restriction useful
on the set directive in OpenACC for example.
Reviewed By: kiranchandramohan
Differential Revision: https://reviews.llvm.org/D90770
Check for duplicate clauses associated with directive. Clauses can appear only once
in the 4 lists associated with each directive (allowedClauses, allowedOnceClauses,
allowedExclusiveClauses, requiredClauses). Duplicates were already present (removed with this
patch) or were introduce in new patches by mistake (D89861).
Reviewed By: kiranchandramohan
Differential Revision: https://reviews.llvm.org/D90241