misc/cgo/testsanitizers: use buffered channel in tsan12.go
os/signal.Notify requires that "the caller must ensure that c has
sufficient buffer space to keep up with the expected signal rate"
as it does a nonblocking send when it receives a signal. The test
currently using a unbuffered channel, which means it may miss the
signal if the signal arrives before the channel receive operation.
Fixes #52998.
Change-Id: Icdcab9396d735506480ef880fb45a4669fa7cc8f
Reviewed-on: https://go-review.googlesource.com/c/go/+/407888 Reviewed-by: Ian Lance Taylor <iant@google.com> Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>