C++: Add summary models for openssl and sqlite

[MathiasVP]

Now that #19443 is merged the model generator gives the models I was looking for in the case of OpenSSL 🎉 So I think this is a good initial set of models.

Commit-by-commit review recommended since I did a small change in fd768ae to filter out which functions we want to generate models for based on the results form the first two commits, and then I redid the models in the next commit.

Note that there are lots of spurious results for the dubious signature consistency check. This check is actually not really representative of the signatures we use in models for C++. In particular, the dubious signature is designed to match signatures like (a,b,c) (with no spaces), but in C++ we can have spaces because of derived types such as (a *,b &,c **), etc. We could probably design a better check for dubious signatures, but I don't really want to get into that right now.

[Copilot]

Pull Request Overview

Adds initial flow summary models for the OpenSSL and SQLite libraries, filters out functions that already have hand-written models or aren’t part of project sources, and updates test expectations accordingly.

• Updated expected test outputs to use new provenance IDs
• Extended CaptureModels.qll to skip existing taint/dataflow models, main, and system headers
• Added a change-note entry announcing the new library models

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

File	Description
cpp/ql/test/library-tests/dataflow/external-models/flow.expected	Updated provenance IDs in expected test output
cpp/ql/src/utils/modelgenerator/internal/CaptureModels.qll	Added imports and filtering predicates to skip pre-modeled/system functions
cpp/ql/src/change-notes/2025-05-14-openssl-sqlite-models.md	Logged the addition of OpenSSL and SQLite flow models

Comments suppressed due to low confidence (1)

cpp/ql/src/utils/modelgenerator/internal/CaptureModels.qll:17

• [nitpick] The alias DataFlow duplicates the module and type name, which may cause confusion when referencing DataFlowFunction. Consider renaming the alias (e.g., DataFlowModels) for clarity.

private import semmle.code.cpp.models.interfaces.DataFlow as DataFlow