Replace android.BuildOs with Config.BuildOS

Replace the android.BuildOs constant with Config.BuildOS so that it
can vary based on the product config.

Bug: 190084016
Test: all Soong tests
Change-Id: Ia67f872d8b2ab788747a22e3a9659dc21c9775cd
diff --git a/sdk/sdk_test.go b/sdk/sdk_test.go
index 97fb248..85e3d87 100644
--- a/sdk/sdk_test.go
+++ b/sdk/sdk_test.go
@@ -15,19 +15,21 @@
 package sdk
 
 import (
-	"android/soong/android"
 	"log"
 	"os"
+	"runtime"
 	"testing"
 
+	"android/soong/android"
+
 	"github.com/google/blueprint/proptools"
 )
 
 // Needed in an _test.go file in this package to ensure tests run correctly, particularly in IDE.
 func TestMain(m *testing.M) {
-	if android.BuildOs != android.Linux {
+	if runtime.GOOS != "linux" {
 		// b/145598135 - Generating host snapshots for anything other than linux is not supported.
-		log.Printf("Skipping as sdk snapshot generation is only supported on %s not %s", android.Linux, android.BuildOs)
+		log.Printf("Skipping as sdk snapshot generation is only supported on linux not %s", runtime.GOOS)
 		os.Exit(0)
 	}