Some clarifications in preparation to automatically order linker dependencies

Test: Browse the code and determine whether it's easier to understand
Bug: 66260943
Change-Id: I88c24a8a31ef68f428919087d206433659265684
diff --git a/cc/rs.go b/cc/rs.go
index 976107e..e7eb3bb 100644
--- a/cc/rs.go
+++ b/cc/rs.go
@@ -82,7 +82,7 @@
 
 func rsFlags(ctx ModuleContext, flags Flags, properties *BaseCompilerProperties) Flags {
 	targetApi := proptools.String(properties.Renderscript.Target_api)
-	if targetApi == "" && ctx.sdk() {
+	if targetApi == "" && ctx.useSdk() {
 		switch ctx.sdkVersion() {
 		case "current", "system_current", "test_current":
 			// Nothing