os/signal: clarify that non-Go thread may change signal mask
Fixes #67773
Change-Id: I05c9934a5b2719d22884c8546f4fadaa9978ac67
Reviewed-on: https://go-review.googlesource.com/c/go/+/589755
Auto-Submit: Ian Lance Taylor <iant@golang.org>
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Commit-Queue: Ian Lance Taylor <iant@google.com> Reviewed-by: Michael Pratt <mpratt@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>