Fix some issues with LOCAL_USES_LIBRARIES

Properly check the value of PRIVATE_ENFORCE_USES_LIBRARIES instead of
only checking that the variable is non-empty.

Change the logic to use product libraries instead of the common ones.
This is required so that dex2oat can find the oat files when stripping
is enabled.

Bug: 70934104
Bug: 67345922
Test: manual

Change-Id: Iee71c2b26f3c0e136a8971ab913725b2b6e100b8