Load versioned llndk.libraries.txt and vndksp.libraries.txt

When ro.vndk.version has a specific VNDK version in it, use the
llndk.libraries.txt and vndksp.libraries.txt files with the version
suffix in the file names.
If ro.vndk.version is "current" or not set, the version suffix will
not be added.
This is to use a proper VNDK snapshot version configuration for a
vendor patition.

Bug: 69531793
Test: In system/etc directory of a Pixel2 device,
  Change llndk.libraries.txt to llndk.libraries.27.txt
  Change vndksp.libraries.txt to vndksp.libraries.27.txt
  Set ro.vndk.version to 27 in vendor/default.prop
  reboot and check if vendor apks work.

Change-Id: I82d83b6805799ea71cc88d1e0297d265a40c0061