Drop dependency on mutex_m

[byroot]

It doesn't really save much effort, and it's being extracted as a gem which cause issues for projects like spring that often are loaded before bundler.

Reported by @tisba

[tisba]

Awesome turnaround time, thanks a lot @byroot! 🥳

[fschwahn]

@byroot This breaks eg. spring-watcher-listen (see https://github.com/rails/spring-watcher-listen/issues/36), as it depends on the synchronize method. Possibly there are other dependencies affected by this.

Maybe instead of patching all dependencies which depend on this synchronize method could be added back to Abstract?

def synchronize(&block)
  @mutex.synchronize(&block(
end

[byroot]

Thanks for the ping.

[fschwahn]

Thank you for the quick turnaround 👍