QEMU TCG tests leave Makefiles behind for Meson

QEMU is moving its Tiny Code Generator (TCG) test suite off hand-maintained Makefiles and onto Meson, aligning that coverage with the rest of the project's test infrastructure.

Pierrick Bouvier posted the work on the QEMU development list as a long series that reimplements TCG tests for every supported architecture, spanning linux-user, softmmu, and multiarch variants. The stated aim is long-term readability and maintainability, and to close the gap that left TCG tests as a special case beside Meson-driven suites.

Under the old setup, test wiring depended on Make string expansion and late discovery of missing pieces. The Meson port declares each target's tests in one place, tracks real dependencies (sources, headers, reference data, plugins, and helper scripts), and fails at configure time when a cross compiler, flag set, or test declaration is wrong, rather than when someone later tries to run the suite. Container-backed cross builds and per-target --cross-cc overrides are expressed as first-class configure options and appear in the Meson summary alongside GDB detection.

Familiar entry points remain: make check-tcg and per-target check-tcg-* still work, with Ninja and meson test available for finer runs. Minimum Meson rises to 1.6 for features the new runner needs. A few unused MIPS user Makefiles stay until those tests are wired in.

Alex Bennée, who had requested follow-ups on an earlier revision, has been reviewing and testing substantial chunks of the series; architecture maintainers including Song Gao have added Reviewed-by tags on LoongArch pieces. Documentation for building and selecting TCG tests is updated to match the new flow.