[clang] [clang][dataflow] Allow `DataflowAnalysisContext` to use a non-owned `Solver`. (PR #91316)

[via cfe-commits]

martinboehme wrote:

> Actually your premerge failure here was an infra issue, but the CI is still broken after this PR somehow: https://lab.llvm.org/buildbot/#/builders/271/builds/7420
> 
> ```
> # .---command stderr------------
> # | error: 'expected-error' diagnostics seen but not expected: 
> # |   (frontend): '-fsyntax-only' action ignored; '-ast-print' action specified previously
> # `-----------------------------
> ```

This is a failure in the test clang\test\OpenMP\target_ast_print.cpp, correct?

Are you sure this PR is the culprit? It touches only the dataflow framework, which is not used in OpenMP or the Clang compiler itself.

https://github.com/llvm/llvm-project/pull/91316