[clang] [analyzer] Improve dangling value tracking in DanglingPtrDeref (PR #211818)

[Gábor Horváth via cfe-commits]

https://github.com/Xazax-hun commented:

Overall, looks good to me once the null pointer case @isuckatcs mentioned is addressed. 

https://github.com/llvm/llvm-project/pull/211818