[clang] [analyzer] Adjust ExprEngine::VisitDeclStmt to ignore `T v=v;` idiom cases for C code (PR #187530)

[Ella Ma via cfe-commits]

Snape3058 wrote:

I checked the behaviors of Sema, the frontend will warn for (1) variables of fundamental types and pointer types in C/C++ that are really uninitialized, (2) variables of reference types and record types in C++. In this update, I make the filter following this pattern.

For record types in C++, as there will always be a ctor call in the AST, they will not hit this filter. The only exception needed to handle in the filter is the reference types.

https://github.com/llvm/llvm-project/pull/187530