Add jni_uses_sdk_apis

NetworkStackTests is using platform APIs for its Java code, but needs
to use portable JNI libraries.  Add a jni_uses_sdk_apis so that it
can select the SDK variants of JNI libraries even though it doesn't
set sdk_version.

Bug: 154665579
Test: atest NetworkStackTests
Change-Id: I841fb761ec1c1ab8596aac44e01eb7eb91428006
diff --git a/java/app.go b/java/app.go
index 0c94e23..c068c46 100755
--- a/java/app.go
+++ b/java/app.go
@@ -80,10 +80,14 @@
 	// list of native libraries that will be provided in or alongside the resulting jar
 	Jni_libs []string `android:"arch_variant"`
 
-	// if true, allow JNI libraries that link against platform APIs even if this module sets
+	// if true, use JNI libraries that link against platform APIs even if this module sets
 	// sdk_version.
 	Jni_uses_platform_apis *bool
 
+	// if true, use JNI libraries that link against SDK APIs even if this module does not set
+	// sdk_version.
+	Jni_uses_sdk_apis *bool
+
 	// STL library to use for JNI libraries.
 	Stl *string `android:"arch_variant"`
 
@@ -234,7 +238,8 @@
 		// If the app builds against an Android SDK use the SDK variant of JNI dependencies
 		// unless jni_uses_platform_apis is set.
 		if a.sdkVersion().specified() && a.sdkVersion().kind != sdkCorePlatform &&
-			!Bool(a.appProperties.Jni_uses_platform_apis) {
+			!Bool(a.appProperties.Jni_uses_platform_apis) ||
+			Bool(a.appProperties.Jni_uses_sdk_apis) {
 			variation = append(variation, blueprint.Variation{Mutator: "sdk", Variation: "sdk"})
 		}
 		ctx.AddFarVariationDependencies(variation, tag, a.appProperties.Jni_libs...)