Include config files to VNDK snapshot

Additionally package ld.config.txt, llndk.libraries.txt,
vndksp.libraries.txt, vndkcore.libraries.txt,
vndkprivate.libraries.txt.

Also defer packaging TARGET_2ND_ARCH build outputs.

Test: m -j vndk dist
Test: development/vndk/snapshot/build.sh
Bug: 66059995
Change-Id: I2a85dde60824126dd16fd3732ddb0af8ae06d934