[openmp] Use Directive_enumSize instead of OMPD_unknown position

[clementval]

Summary

Previously OMPD_unknown was last item in the Directive enumeration and its position was
used in various comparison and assertion. With the new Directive enumeration, this should be
change with llvm::omp::Directive_enumSize. This patch fix two place where it was not done in
D81736.

[clementval]

add unsigned cast

[jdoerfert]

LGTM, maybe a minor adjustment necessary.

clang/lib/Basic/OpenMPKinds.cpp

583

<, right?

[clementval]

clang/lib/Basic/OpenMPKinds.cpp

583

You are right.

clang/lib/Basic/OpenMPKinds.cpp

return Kind == OMPD_distribute_parallel_for ||
          Kind == OMPD_teams_distribute_parallel_for ||
          Kind == OMPD_target_teams_distribute_parallel_for ||
          Kind == OMPD_target_teams_distribute_parallel_for_simd;
 }
 
 void clang::getOpenMPCaptureRegions(
     SmallVectorImpl<OpenMPDirectiveKind> &CaptureRegions,
     OpenMPDirectiveKind DKind) {
-  assert(DKind <= OMPD_unknown);
+  assert(unsigned(DKind) < llvm::omp::Directive_enumSize);
   switch (DKind) {
   case OMPD_parallel:
   case OMPD_parallel_for:
   case OMPD_parallel_for_simd:
   case OMPD_parallel_master:
   case OMPD_parallel_sections:
   case OMPD_distribute_parallel_for:
   case OMPD_distribute_parallel_for_simd:

clang/lib/Parse/ParseOpenMP.cpp

for (unsigned I = 0; I < llvm::array_lengthof(F); ++I) {
     if (SDKind == OMPD_unknown)
       continue;
 
     if (SDKind == F[I][1]) {
       P.ConsumeToken();
       DKind = F[I][2];
     }
   }
-  return DKind < OMPD_unknown ? static_cast<OpenMPDirectiveKind>(DKind)
-                              : OMPD_unknown;
+  return unsigned(DKind) < llvm::omp::Directive_enumSize
+             ? static_cast<OpenMPDirectiveKind>(DKind)
 }
 
 static DeclarationName parseOpenMPReductionId(Parser &P) {
   Token Tok = P.getCurToken();
   Sema &Actions = P.getActions();
   OverloadedOperatorKind OOK = OO_None;
   // Allow to use 'operator' keyword for C++ operators
   bool WithOperator = false;