threading: support for GGML_SCHED_PRIO_LOW, update thread info on Windows to avoid...

threading: support for GGML_SCHED_PRIO_LOW, update thread info on Windows to avoid throttling (llama/12995)

* threading: support for GGML_SCHED_PRIO_LOW, update thread info on Windows to avoid throttling

We talked about adding LOW priority for GGML threads in the original threadpool PR.
It might be useful for some cases to avoid contention.

Latest Windows ARM64 releases started parking (offlining) the CPU cores
more aggresively which results in suboptimal performance with n_threads > 4.
To deal with that we now disable Power Throttling for our threads for the NORMAL
and higher priorities.

Co-authored-by: Diego Devesa <redacted>
* threading: disable SetThreadInfo() calls for older Windows versions

* Update tools/llama-bench/llama-bench.cpp

Co-authored-by: Diego Devesa <redacted>
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Co-authored-by: Diego Devesa <redacted>