syscall: don't defer close raw Socketpair fds in tests
The raw fds are successively wrapped using os.NewFile and will be closed
by (*os.File).Close. Avoids a double close, in the worst case closing an
unrelated fd.
Change-Id: I86aabe5ed865eff43d264ddae1fb07c935868e97
Reviewed-on: https://go-review.googlesource.com/c/go/+/309353
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>