metal : enable ggml-alloc (#2627)
* metal: enable ggml-alloc
Make ggml-alloc work with concurrently dispatch.
* style-fix
Co-authored-by: slaren <slarengh@gmail.com>
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Co-authored-by: slaren <slarengh@gmail.com>
Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
