[clang] [Clang] Fix build of PackIndexingTypeLocs (PR #232194)

[Kazu Hirata via cfe-commits]

================
@@ -1300,9 +1300,7 @@ static QualType ConvertDeclSpecToType(TypeProcessingState &state) {
   case DeclSpec::TST_typename_pack_indexing: {
     Expr *E = DS.getPackIndexingExpr();
     assert(E && "Didn't get an expression for pack indexing");
----------------
kazutakahirata wrote:

Should we remove these two lines now that `E` is not used anymore? Would that allow us to simplify or even remove the `if (T == TST_typename_pack_indexing)` handling in `SetTypeSpecType` in `DeclSpec.cpp`?

```suggestion
```

https://github.com/llvm/llvm-project/pull/232194