Fix flang after D76342

Fix Flang build after addition of a new OpenMP clauses for a clang patch (D76342).
Flang is using TableGen to generation the declaration of clause checks and the new clause
was missing a definiton.

Reviewed By: klausler

Differential Revision: https://reviews.llvm.org/D96808

GitOrigin-RevId: b86dbe0c23e3d284699da551afc2ca9c634a6c62
diff --git a/lib/Semantics/check-omp-structure.cpp b/lib/Semantics/check-omp-structure.cpp
index 4a9192d..e31b2bf 100644
--- a/lib/Semantics/check-omp-structure.cpp
+++ b/lib/Semantics/check-omp-structure.cpp
@@ -667,6 +667,7 @@
 CHECK_SIMPLE_CLAUSE(Relaxed, OMPC_relaxed)
 CHECK_SIMPLE_CLAUSE(SeqCst, OMPC_seq_cst)
 CHECK_SIMPLE_CLAUSE(Simd, OMPC_simd)
+CHECK_SIMPLE_CLAUSE(Sizes, OMPC_sizes)
 CHECK_SIMPLE_CLAUSE(TaskReduction, OMPC_task_reduction)
 CHECK_SIMPLE_CLAUSE(To, OMPC_to)
 CHECK_SIMPLE_CLAUSE(UnifiedAddress, OMPC_unified_address)