cb94e82502
Enable GBM (required by the EGL/GBM/GLES2 surface used by Qt6/KWin). Drop crocus/iris from the gallium driver set for the 26.1.4 build — the Intel hardware drivers require DRM uapi surfaces that are not available in the Redox sysroot yet. They MUST be restored when the Intel DRM/redox-drm path matures (tracked in local/docs/DRM-MODERNIZATION-EXECUTION-PLAN.md Stage 5); this is a build-surface constraint, not a feature removal. Also widen the -Wno-error set for the 26.1.4 cross-compile (missing-prototypes, return-type, empty-body, incompatible-pointer-types, int-conversion, format) — upstream Mesa enables -Werror by default and the Redox sysroot headers trip these classes; the underlying warnings remain visible in the build log.