[clang] [analyzer] Fix crash in Stream checker when using void pointers (PR #97199)

[Donát Nagy via cfe-commits]

NagyDonat wrote:

_I only noticed that this PR was already merged after posting the review. There is no need to revert the commit -- it's better than nothing -- but I'd be happy if you created a followup change that also handles the testcase that I mentioned._

https://github.com/llvm/llvm-project/pull/97199