Widevine is broken on C57 on macOS

[bbondy]

For widevine not working:
otool -L widevinecdmadapter.plugin

This widevinecdmadapter.plugin is bundled by us in our app.

Previously the .plugin depended on:
@loader_path/libwidevinecdm.dylib

But on C57 it checks:
WidevineCdm/_platform_specific/mac_x64/libwidevinecdm.dylib

Test cases: Test that netflix plays videos cross platform. Use a fresh profile.