Adjust the double loadable check

The check no longer tracks private dependencies like stubImplDepTag and
staticVariantTag. It also doesn't do the check for double_loadable
libraries that are not depended on by a LLNDK library.

Bug: N/A
Test: m
Test: add 'double_loadable: true, gen_trace: true` to an aidl_interface
module. The build doesn't break.

Change-Id: Iccd1a9d445a48d03c373708ba1bdd34b9a7f152d