os: package initialization hangs is Stdin is blocked [1.25 backport]

[gopherbot]

@qmuntal requested issue #76391 to be considered for backport to the next 1.25 minor release.

@gopherbot please backport to Go 1.25. This is a regression introduced in Go 1.25 that can cause hangs while initializing the standard library.

[gopherbot]

Change https://go.dev/cl/725580 mentions this issue: [release-branch.go1.25] os,internal/poll: don't call IsNonblock for consoles and Stdin

[gopherbot]

Closed by merging CL 725580 (commit 93f5d1c) to release-branch.go1.25.