Add OS to configuration key in mixed builds

This also removes the special-case filegroup from mixed builds
buildroot; no special handling is required. Since we're currently
hardcoding linux_x86_64 as our host platform, it should be fine
to continue assumping that hardcoded host for now.

Test: USE_BAZEL_ANALYSIS=1 m adbd
Change-Id: I35509f4eb33ba7a243fab4c34b35958f6f2fceab
diff --git a/android/bazel_handler_test.go b/android/bazel_handler_test.go
index fe66a90..ad5b63b 100644
--- a/android/bazel_handler_test.go
+++ b/android/bazel_handler_test.go
@@ -9,11 +9,11 @@
 
 func TestRequestResultsAfterInvokeBazel(t *testing.T) {
 	label := "//foo:bar"
-	arch := Arm64
+	cfg := configKey{Arm64, Android}
 	bazelContext, _ := testBazelContext(t, map[bazelCommand]string{
-		bazelCommand{command: "cquery", expression: "deps(@soong_injection//mixed_builds:buildroot, 2)"}: `//foo:bar|arm64>>out/foo/bar.txt`,
+		bazelCommand{command: "cquery", expression: "deps(@soong_injection//mixed_builds:buildroot, 2)"}: `//foo:bar|arm64|android>>out/foo/bar.txt`,
 	})
-	g, ok := bazelContext.GetOutputFiles(label, arch)
+	g, ok := bazelContext.GetOutputFiles(label, cfg)
 	if ok {
 		t.Errorf("Did not expect cquery results prior to running InvokeBazel(), but got %s", g)
 	}
@@ -21,7 +21,7 @@
 	if err != nil {
 		t.Fatalf("Did not expect error invoking Bazel, but got %s", err)
 	}
-	g, ok = bazelContext.GetOutputFiles(label, arch)
+	g, ok = bazelContext.GetOutputFiles(label, cfg)
 	if !ok {
 		t.Errorf("Expected cquery results after running InvokeBazel(), but got none")
 	} else if w := []string{"out/foo/bar.txt"}; !reflect.DeepEqual(w, g) {