windows: remove unreachable return statement in Proc.Call

Change-Id: I5bb10469bab144f5e42c7bcf6ee8717d3fd0d4e4
Reviewed-on: https://go-review.googlesource.com/47337
Reviewed-by: Matt Layher <mdlayher@gmail.com>
Run-TryBot: Matt Layher <mdlayher@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
1 file changed