[clang] Reland "[OpenMP][TR12] change property of map-type modifier." (PR #90935)

[Vitaly Buka via cfe-commits]

vitalybuka wrote:

```
diff --git a/clang/lib/Parse/ParseOpenMP.cpp b/clang/lib/Parse/ParseOpenMP.cpp
index 53d89ce2fa3e..1a4442f38f6d 100644
--- a/clang/lib/Parse/ParseOpenMP.cpp
+++ b/clang/lib/Parse/ParseOpenMP.cpp
@@ -4326,6 +4326,7 @@ static OpenMPMapClauseKind isMapType(Parser &P) {
   OpenMPMapClauseKind MapType =
       static_cast<OpenMPMapClauseKind>(getOpenMPSimpleClauseType(
           OMPC_map, PP.getSpelling(Tok), P.getLangOpts()));
+  assert((int)MapType < 6);
   return MapType;
 }
```

https://github.com/llvm/llvm-project/pull/90935