build: windows/arm (32-bit ARM) port is broken #70705

The Go porting policy has a section on broken ports, https://go.dev/wiki/PortingPolicy#broken-ports. The GOOS=windows GOARCH=arm (not arm64) port was marked broken in August 2024 (CL 601777) for the following reasons:

• The port stopped working, failing to build with make.bat, tracked in issue runtime: problem with preemption on windows arm32 #68552.
• The builder stopped running, and no new running builder has been added yet, tracked in x/build: add LUCI windows-arm builder #67308. (A running builder is needed to know whether the port is working.)

This is an umbrella issue to track the status of the port.

CC @golang/windows, @golang/release.