Fix windows build by moving references to SIGUSR2 into a file not built (#6422)

on windows.

command/commands.go

@@ -629,20 +629,3 @@ func MakeSighupCh() chan struct{} {
 	}()
 	return resultCh
 }
-
-// MakeSigUSR2Ch returns a channel that can be used for SIGUSR2
-// goroutine logging. This channel will send a message for every
-// SIGUSR2 received.
-func MakeSigUSR2Ch() chan struct{} {
-	resultCh := make(chan struct{})
-
-	signalCh := make(chan os.Signal, 4)
-	signal.Notify(signalCh, syscall.SIGUSR2)
-	go func() {
-		for {
-			<-signalCh
-			resultCh <- struct{}{}
-		}
-	}()
-	return resultCh
-}

command/commands_nonwindows.go

@@ -0,0 +1,26 @@
+// +build !windows
+
+package command
+
+import (
+	"os"
+	"os/signal"
+	"syscall"
+)
+
+// MakeSigUSR2Ch returns a channel that can be used for SIGUSR2
+// goroutine logging. This channel will send a message for every
+// SIGUSR2 received.
+func MakeSigUSR2Ch() chan struct{} {
+	resultCh := make(chan struct{})
+
+	signalCh := make(chan os.Signal, 4)
+	signal.Notify(signalCh, syscall.SIGUSR2)
+	go func() {
+		for {
+			<-signalCh
+			resultCh <- struct{}{}
+		}
+	}()
+	return resultCh
+}

command/commands_windows.go

@@ -0,0 +1,8 @@
+// +build windows
+
+package command
+
+// MakeSigUSR2Ch does nothing useful on Windows.
+func MakeSigUSR2Ch() chan struct{} {
+	return make(chan struct{})
+}