Use drop-in mutex through build tags

[piotrm50]

Description of change

FakeRWMutex is used as a drop-in replacement for a regular mutex through the use of a fakemutex buildtag. Alternatively deadlock tag can be used to use a deadlock detection mutex. If neither tag is specified, a real sync.Mutex or sync.RWMutex is used.

Type of change

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• Enhancement (a non-breaking change which adds functionality)

How the change has been tested

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Make sure to provide instructions for the maintainer as well as any relevant configurations.

Change checklist

Add an x to the boxes that are relevant to your changes, and delete any items that are not.

• [ ] My code follows the contribution guidelines for this project
• [ ] I have performed a self-review of my own code
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] New and existing unit tests pass locally with my changes