Add host required arguments to FontFamily_getVariant

Native critical methods are not supported when running on host JVM. They
need the environment and class arguments. To add those only for host,
this uses specially defined macros.

Bug: 74062470
Test: lunch sdk && m libandroid_runtime
Change-Id: I9efff6e4f1132f0566e72c6c91ab101d10c1406a