os,internal/poll: don't call IsNonblock for consoles and Stdin

os,internal/poll: don't call IsNonblock for consoles and Stdin

windows.IsNonblock can block for synchronous handles that have an
outstanding I/O operation. Console handles are always synchronous, so
we should not call IsNonblock for them. Stdin is often a pipe, and
almost always a synchronous handle, so we should not call IsNonblock for
it either. This avoids potential deadlocks during os package
initialization, which calls NewFile(syscall.Stdin).

Fixes #75949
Updates #76391

Cq-Include-Trybots: luci.golang.try:gotip-windows-amd64-longtest,gotip-windows-amd64-race,gotip-windows-arm64
Change-Id: I1603932b0a99823019aa0cad960f94cee9996505
Reviewed-on: https://go-review.googlesource.com/c/go/+/724640
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dneil@google.com>
Auto-Submit: Damien Neil <dneil@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>