[clang] [clang][AST] Reduce some AST node size. (PR #142585)

[Yanzuo Liu via cfe-commits]

================
@@ -745,6 +755,16 @@ class alignas(void *) Stmt {
     unsigned TemplateDepth;
   };
 
+  class ChooseExprBitfields {
+    friend class ASTStmtReader;
+    friend class ChooseExpr;
+
+    LLVM_PREFERRED_TYPE(ExprBitfields)
+    unsigned : NumExprBits;
+
+    bool CondIsTrue : 1;
----------------
zwuis wrote:

```suggestion
    LLVM_PREFERRED_TYPE(bool)
    unsigned CondIsTrue : 1;
```


https://github.com/llvm/llvm-project/pull/142585