[clang] [StaticAnalyzer] Fix InnerPointerBRVisitor to avoid repeated map scans (PR #185796)

[Gábor Horváth via cfe-commits]

Xazax-hun wrote:

It looks like the `Analysis/inner-pointer.cpp` test fails. The PR must change the semantics of something. Could you look into this?

https://github.com/llvm/llvm-project/pull/185796