[OPENMP] Initial support for 'depend' clause (4.0).

Parsing and sema analysis (without support for array sections in arguments) for 'depend' clause (used in 'task' directive, OpenMP 4.0).

llvm-svn: 240409

clang/lib/CodeGen/CGStmtOpenMP.cpp

@@ -2041,6 +2041,7 @@ static void EmitOMPAtomicExpr(CodeGenFunction &CGF, OpenMPClauseKind Kind,
   case OMPC_nowait:
   case OMPC_untied:
   case OMPC_threadprivate:
+  case OMPC_depend:
   case OMPC_mergeable:
     llvm_unreachable("Clause is not allowed in 'omp atomic'.");
   }