Mark libpiex vendor_available.

libpiex belongs to vndk-cap. Mark it vendor_available to enable vndk abi
stability checks on it.

Details: https://android-review.googlesource.com/368372

Test: mm -j64

Bug: 38244611

Merged-In: Ic5bba201b52abe6ab985fabcb04811f97cd9cae5
Change-Id: I33f9c4bf15a33d5792cbe617420a1c48baf492e6
(cherry picked from commit 666035422526cc47f047664c9587ea631d419620)
1 file changed