Backports a bugfix of the Clang Static Analyzer to clang-14

[steakhal]

The commit fixes a bug in the apiModeling.llvm.CastValue checker, where the new MLIR constructs formed a null-pointer which it immediately dereferenced causing a crash.
It would be grate to backport this fix since clang-tidy users of LLVM developers would likely encounter this crash.
Due to the clang-tidy integration to clangd even wider scale of developers might be affected.
Consequently, I think this patch deserves to be backported.

Should I create a followup patch mentioning this in some release notes?

/cherry-pick c7fa4e8

[llvmbot]

@llvm/issue-subscribers-clang-tidy

[llvmbot]

@llvm/issue-subscribers-clang-static-analyzer

[llvmbot]

Failed to cherry-pick: c7fa4e8

https://github.com/llvm/llvm-project/actions/runs/2459824107

Please manually backport the fix and push it to your github fork. Once this is done, please add a comment like this:

/branch <user>/<repo>/<branch>

[steakhal]

/branch steakhal/llvm-project/backport-c7fa4e8a8bc41e52cc49a27e0495d67d730fa167

[llvmbot]

Failed to create pull request for backport-c7fa4e8a8bc41e52cc49a27e0495d67d730fa167 https://github.com/llvm/llvm-project/actions/runs/2460431761

[steakhal]

@tstellar
It had the following error github.GithubException.GithubException: 422 {"message": "Validation Failed", "errors": [{"resource": "PullRequest", "field": "head", "code": "invalid"}], "documentation_url": "https://docs.github.com/rest/reference/pulls#create-a-pull-request"}, and I'm not sure how to proceed.