Replace jniDependencyTag with a value

Support GetDirectDepsWithTag on JNI deps by replacing the
jniDependencyTag type with a jniLibTag value.

Test: app_test.go
Change-Id: I8d66a5d3f433562e131a1fbafce75891d1b094dd

java/app.go

@@ -379,7 +379,6 @@ func (a *AndroidApp) DepsMutator(ctx android.BottomUpMutatorContext) {
 			"can only be set for modules that set sdk_version")
 	}
 
-	tag := &jniDependencyTag{}
 	for _, jniTarget := range ctx.MultiTargets() {
 		variation := append(jniTarget.Variations(),
 			blueprint.Variation{Mutator: "link", Variation: "shared"})
@@ -393,7 +392,7 @@ func (a *AndroidApp) DepsMutator(ctx android.BottomUpMutatorContext) {
 			Bool(a.appProperties.Jni_uses_sdk_apis) {
 			variation = append(variation, blueprint.Variation{Mutator: "sdk", Variation: "sdk"})
 		}
-		ctx.AddFarVariationDependencies(variation, tag, a.appProperties.Jni_libs...)
+		ctx.AddFarVariationDependencies(variation, jniLibTag, a.appProperties.Jni_libs...)
 	}
 
 	a.usesLibrary.deps(ctx, sdkDep.hasFrameworkLibs())

java/java.go

@@ -547,13 +547,8 @@ type dependencyTag struct {
 	name string
 }
 
-type jniDependencyTag struct {
-	blueprint.BaseDependencyTag
-}
-
 func IsJniDepTag(depTag blueprint.DependencyTag) bool {
-	_, ok := depTag.(*jniDependencyTag)
-	return ok
+	return depTag == jniLibTag
 }
 
 var (
@@ -573,6 +568,7 @@ var (
 	instrumentationForTag = dependencyTag{name: "instrumentation_for"}
 	usesLibTag            = dependencyTag{name: "uses-library"}
 	extraLintCheckTag     = dependencyTag{name: "extra-lint-check"}
+	jniLibTag             = dependencyTag{name: "jnilib"}
 )
 
 func IsLibDepTag(depTag blueprint.DependencyTag) bool {
@@ -1001,7 +997,7 @@ func (j *Module) collectDeps(ctx android.ModuleContext) deps {
 		otherName := ctx.OtherModuleName(module)
 		tag := ctx.OtherModuleDependencyTag(module)
 
-		if _, ok := tag.(*jniDependencyTag); ok {
+		if IsJniDepTag(tag) {
 			// Handled by AndroidApp.collectAppDeps
 			return
 		}