tools : enable kvu in perplexity for hellaswag, winogrande, multiple-choice (#19954)

tools : enable kvu in perplexity for hellaswag, winogrande, multiple-choice (#19954)

llama-perplexity -hf unsloth/Qwen3-0.6B-GGUF:Q4_K_M -f winogrande-debiased-eval.csv --winogrande

    winogrande_score : tokenizing selected tasks
    winogrande_score : calculating winogrande score over selected tasks.
    split_equal: sequential split is not supported when there are coupled sequences in the input batch (you may need to use the -kvu flag)
    decode: failed to find a memory slot for batch of size 46
    failed to decode the batch, n_batch = 2048, ret = 1
    winogrande_score: llama_decode() failed

same for hellaswag:

    split_equal: sequential split is not supported when there are coupled sequences in the input batch (you may need to use the -kvu flag)
    decode: failed to find a memory slot for batch of size 99
    failed to decode the batch, n_batch = 2048, ret = 1
    hellaswag_score: llama_decode() failed

Signed-off-by: Adrien Gallouët <redacted>