Make avs_list work without typeof
Make avs_list work without typeof

Summary:
- Fix AVS_LIST operations when typeof is unavailable
- Fix compilation errors in avs_list tests with no typeof

Test Plan: make check

Reviewers: kfyatek, mkrawiec

Maniphest Tasks: T773

Differential Revision: https://phabricator.avsystem.com/D2828

AVSystem/avs_commons,AVSystem/avs_commons,AVSystem/avs_commons,AVSystem/avs_commons