ggml : use OpenMP as a thread pool (llama/7606)

ggml : use OpenMP as a thread pool (llama/7606)

* ggml: Added OpenMP for multi-threads processing

* ggml : Limit the number of threads used to avoid deadlock

* update shared state n_threads in parallel region

* clear numa affinity for main thread even with openmp

* enable openmp by default

* fix msvc build

* disable openmp on macos

* ci : disable openmp with thread sanitizer

* Update ggml.c

Co-authored-by: Georgi Gerganov <redacted>
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Co-authored-by: slaren <redacted>
Co-authored-by: Georgi Gerganov <redacted>