test: skip test/fixedbugs/bug345.go on windows
test: skip test/fixedbugs/bug345.go on windows

Before the CL 115277 we did not run the test on Windows,
so let's just go back to not running the test on Windows.
There is nothing OS-specific about this test,
so skipping it on Windows doesn't seem like a big deal.

Updates #25693
Fixes #25586

Change-Id: I1eb3e158b322d73e271ef388f8c6e2f2af0a0729
Reviewed-on: https://go-review.googlesource.com/115857
Run-TryBot: Yury Smolsky <f26331c55f2e9b348f65eb11cafdbe38d0f7ac5e@smolsky.by>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

josharian/go,cloudflare/go,josharian/go,josharian/go,akutz/go,cloudflare/go,CAFxX/go,josharian/go,golang/go,nawawi/go,akutz/go,CAFxX/go,golang/go,CAFxX/go,golang/go,CAFxX/go,josharian/go,akutz/go,akutz/go,CAFxX/go,nawawi/go,cloudflare/go,josharian/go,golang/go,akutz/go,akutz/go,golang/go,CAFxX/go,nawawi/go,cloudflare/go,CAFxX/go,cloudflare/go,nawawi/go,josharian/go,nawawi/go,cloudflare/go,golang/go,nawawi/go,cloudflare/go,nawawi/go,akutz/go,golang/go,CAFxX/go,josharian/go,golang/go,cloudflare/go,akutz/go,nawawi/go