[llvm] [analyzer] Add missing include <unordered_map> to llvm/lib/Support/Z3Solver.cpp (PR #106410)

[Tamir Duberstein via llvm-commits]

tamird wrote:

Will also need to be cherry-picked in https://github.com/llvm/llvm-project/tree/release/19.x.

https://github.com/llvm/llvm-project/pull/106410