Add some support for CPU profiling

luprex/core/cpp/util.hpp

@@ -37,6 +37,9 @@ using LuaSourcePtr = std::unique_ptr<LuaSourceVec>;
 using HashValue = std::pair<uint64_t, uint64_t>;
 using IdVector = std::vector<int64_t>;
 
+// Return nanoseconds elapsed, for profiling purposes.
+int64_t profiling_clock();
+
 // Return true if the string is a valid lua identifier.
 bool is_identifier(const std::string &str);