[clang] [clang] [CodeGen] fix crash when Ty isDependentType in CodeGenFunction::EmitAutoVarAlloca (PR #135643)

[via cfe-commits]

MacroModel wrote:

I encountered this problem when compiling my own project.
```bash
git clone https://github.com/MacroModel/uwvm2.git --depth=1
cd uwvm2
xmake f -m debug --use-llvm=y
xmake -v
```

https://github.com/llvm/llvm-project/pull/135643