The new ace-step.cpp revision moves backend initialization inside each
`*_load` call and drops the separate `DiTGGMLConfig` argument from
`dit_ggml_load` (config now lives in `DiTGGML::cfg`, populated from GGUF
metadata at load time). Drop the now-removed `*_init_backend` calls and
replace `g_dit_cfg` accesses with `g_dit.cfg`.
Assisted-by: Claude:claude-opus-4-7 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Co-authored-by: Ettore Di Giacinto <mudler@localai.io>
