sync: fix goroutine leak for when TestMutexFairness times out
If the timeout triggers before writing to the done channel, the
goroutine will be blocked waiting for a corresponding read that’s
no longer existent, thus a goroutine leak. This change fixes that by
using a buffered channel instead.
Change-Id: I9cf4067a58bc5a729ab31e4426edd78bd359e8e0
GitHub-Last-Rev:
a7d811a7be6d875175a894e53d474aa0034e7d2c
GitHub-Pull-Request: golang/go#40236
Reviewed-on: https://go-review.googlesource.com/c/go/+/242902
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>