[clang] [clang]Avoid to check created local variable multiple time when evaluating (PR #69106)

[Erich Keane via cfe-commits]

erichkeane wrote:

> I test example in branch llvmorg-16.0.6,ExprConstant.cpp also has this assertion but it will not result in crash.So I think you should not remove this assertion and try to find the reason `!Result.isAbsent()` Maybe its valueKind changed somewhere(just my guess).

I agree here, we shouldn't be double-creating variables like this, removing the assert doesn't seem right to me.

https://github.com/llvm/llvm-project/pull/69106