Switched to header only spdlog for better portability

thirdparty/spdlog/details/null_mutex.h

@@ -0,0 +1,49 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+#include <atomic>
+#include <utility>
+// null, no cost dummy "mutex" and dummy "atomic" int
+
+namespace spdlog {
+namespace details {
+struct null_mutex
+{
+    void lock() const {}
+    void unlock() const {}
+    bool try_lock() const
+    {
+        return true;
+    }
+};
+
+struct null_atomic_int
+{
+    int value;
+    null_atomic_int() = default;
+
+    explicit null_atomic_int(int new_value)
+        : value(new_value)
+    {}
+
+    int load(std::memory_order = std::memory_order_relaxed) const
+    {
+        return value;
+    }
+
+    void store(int new_value, std::memory_order = std::memory_order_relaxed)
+    {
+        value = new_value;
+    }
+
+    int exchange(int new_value, std::memory_order = std::memory_order_relaxed)
+    {
+        std::swap(new_value, value);
+        return new_value; // return value before the call
+    }
+};
+
+} // namespace details
+} // namespace spdlog