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