ci: use sccache on windows instead of ccache

[ochafik]

As advised on https://github.com/hendrikmuhs/ccache-action

Fixes the Windows SYCL build caused by #11516 (example failure)

(Cc/ @ggerganov ref)

[slaren]

Please let the second HIP run finish to make sure that it is working. Considering the size of the cache I suspect that sccache may not be compatible with the HIP compiler.

Save cache using key "sccache-windows-latest-cmake-hip-2025-01-31T15:17:55.700Z".
"C:\Program Files\Git\usr\bin\tar.exe" --posix -cf cache.tzst --exclude cache.tzst -P -C D:/a/llama.cpp/llama.cpp --files-from manifest.txt --force-local --use-compress-program "zstd -T0"
Cache Size: ~8 MB (7945703 B)
Cache saved successfully

[ochafik]

Please let the second HIP run finish to make sure that it is working

@slaren It's finally green!

Considering the size of the cache I suspect that sccache may not be compatible with the HIP compiler.

Urgh good catch, we'll need to play w/ CMAKE_HIP_COMPILER_LAUNCHER (ROCm/ROCm#2817), will send separately.

[slaren]

ccache seems to work with HIP (https://github.com/ggerganov/llama.cpp/actions/runs/13012980277/job/36294999875), so if you cannot make sccache work it can always be reverted to ccache.