`examples/toolchains/go_toolchain` does not support Windows builds

[Dimagog]

Trying to build helloworld Go:

E:\WorkExt\buck2\examples\toolchains\go_toolchain>buck2 build //...
Could not connect to buck2 daemon (buck2 daemon is not running), killing daemon..
Connected to new buck2 daemon.
Build ID: 7ec307a7-b7c0-4c57-bf66-8483a4ec0e6f
Loading targets.     Remaining     0/13
Analyzing targets.   Remaining     0/29
Command: build.
Time elapsed: 4.7s
BUILD FAILED
Error running analysis for `root//helloworld:helloworld (prelude//platforms:default#97667764a66ee3d4)`

Caused by:
    0: Error in configured node dependency, dependency chain follows (-> indicates depends on, ^ indicates same configuration as previous):
              root//helloworld:helloworld (prelude//platforms:default#97667764a66ee3d4)
           -> root//helloworld:helloworld (prelude//platforms:default#404a521648d9de05)
           -> toolchains//:go (^)

    1: Error checking compatibility of `prelude//go/tools:tool_pack` with `prelude//platforms:default#b6ba4ffd7ac40407`
    2: Error in configured node dependency, dependency chain follows (-> indicates depends on, ^ indicates same configuration as previous):
              prelude//go/tools:tool_pack (prelude//platforms:default#b6ba4ffd7ac40407)
           -> toolchains//:go_bootstrap (^)

    3: configuring attr `env_go_os`
    4: None of 2 conditions matched configuration `prelude//platforms:default#b6ba4ffd7ac40407` and no default was set:
         prelude//os:linux
         prelude//os:macos

Using latest tag of buck2 itself:

E:\WorkExt\buck2\examples\toolchains\go_toolchain>git st
HEAD detached at latest
You are currently bisecting, started from branch 'main'.
  (use "git bisect reset" to get back to the original branch)

nothing to commit, working tree clean

E:\WorkExt\buck2\examples\toolchains\go_toolchain>git log -1
commit 8c23ffd5c8ecad5acff2f8472ac431ce5d2134c4 (HEAD, tag: latest)
Author: Chenhao Zuo <nero@meta.com>
Date:   Sat Mar 14 15:08:16 2026 -0700

    Make tokio an optional dependency in pagable crate