Partial reverts of vndk-apex

This installs vndk libs under system/lib/vndk
instead of vndk-apex.
(Partial reverts of 31c470b5)

Also fixes the bug 097087be brought.
This produced incomplete list of vndkcorevariant.libraries.txt.

Bug: 143374795
Test: m && boot
Change-Id: I17864de4770a84431756e0c3765b601d3dc2abb1