vndk-def: Sort ELFLinkData by path

This commit adds __lt__() to ELFLinkData class so that instances of
ELFLinkData can be sorted by path by default.

This commit also adds several sorted() function calls so that the
output can be stable between different command line invocations.

Test: ./tests/run.py
Test: Run check-dep subcommand multiple times and compare the output.
Change-Id: I08bf7a9e0e1e393f0e0f3fcd4cf83a4002515b51