[libunwind] [docs] Minor fix to outdated example in LibTooling tutorial (PR #67262)

llvmbot wrote: @llvm/pr-subscribers-clang Changes Came across this while using said tutorial. I grabbed this example from [ASTMatchers tutorial](https://clang.llvm.org/docs/LibASTMatchersTutorial.html) for consistency, and it works with the latest LLVM version. --- Full diff: https://g

[libunwind] [docs] Minor fix to outdated example in LibTooling tutorial (PR #67262)

https://github.com/hhkit created https://github.com/llvm/llvm-project/pull/67262 Came across this while using said tutorial. I grabbed this example from [ASTMatchers tutorial](https://clang.llvm.org/docs/LibASTMatchersTutorial.html) for consistency, and it works with the latest LLVM version.