Slicer: Create an NDK version

Add a slicer_ndk static library that is built with the NDK and
can thus be properly used with NDK-only apps, e.g., CTS.

Factor out commonality into a defaults block.

Bug: 65016018
Bug: 70901841
Test: mmma tools/dexter/slicer
Change-Id: I531d3d12da83fa2aabf99e1ab5eec35a655a997c