Add sdk_library_test.go to Android.bp file

When this file was initially created by extracting the test from the
java_test.go file it was not added to Android.bp file so was not being
built and tested as it should. That lead to a recent change that left
it unable to compile. This change corrects both those issues.

Bug: 186723288
Bug: 179354495
Test: m nothing
Change-Id: I06f32bb572f57b6df3c772f1d9d21fe323fbf353