Re: [PATCH v2 4/4] ThreadSanitizer: add suppressions

> Add a file .tsan-suppressions and list two functions in it: want_color()
> and transfer_debug(). Both of these use the pattern
> 
> 	static int foo = -1;
> 	if (foo < 0)
> 		foo = bar();
> 
> where bar always returns the same non-negative value. This can cause
> ThreadSanitizer to diagnose a race when foo is written from two threads.
> That is indeed a race, although it arguably doesn't matter in practice
> since it's always the same value that is written.
> 
> Add NEEDSWORK-comments to the functions so that this problem is not
> forever swept way under the carpet.
> 
> The suppressions-file is used by setting the environment variable
> TSAN_OPTIONS to, e.g., "suppressions=$(pwd)/.tsan-suppressions". Observe
> that relative paths such as ".tsan-suppressions" might not work.