fix: rpc-server cache may not work in Windows environments (#22394)

* fix: create directory and log cache file name.

* Remove GGML_LOG_INFO conditional compilation.

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Co-authored-by: kotaro <kotaro.kusunoki@gmail.com>

ggml/src/ggml-rpc/ggml-rpc.cpp

@@ -1101,7 +1101,7 @@ bool rpc_server::set_tensor(const std::vector<uint8_t> & input) {
         fs::path cache_file = fs::path(cache_dir) / hash_str;
         std::ofstream ofs(cache_file, std::ios::binary);
         ofs.write((const char *)data, size);
-        GGML_LOG_INFO("[%s] saved to '%s'\n", __func__, cache_file.c_str());
+        GGML_LOG_INFO("[%s] saved to '%s'\n", __func__, cache_file.string().c_str());
     }
     ggml_backend_tensor_set(tensor, data, offset, size);
     return true;