ColorSpaceHelpers.cpp directly uses std::mutex rather than our Mutex wrappers

Same goes for the std::lock_guard. Should this be replaced with Mutex and AutoMutex ?

Start in ColorSpaceHelpers.cpp and inspect how std::mutex and std::lock_guard are used, then compare nearby code for the project's Mutex and AutoMutex wrappers. Confirm the intended convention with existing wrapper usage; done means the direct standard mutex types are replaced if appropriate and the change remains consistent with the surrounding implementation.

Written by the indexing model from the issue text.