Set apex_available property

The marked library(ies) were available to the APEXes via the
hand-written whitelist in build/soong/apex/apex.go. Trying to remove the
whitelist by adding apex_available property to the Android.bp of the
libraries.

Exempt-From-Owner-Approval: approved by enh

Bug: 150999716
Test: m
Merged-In: If51a7e80f4aed7495cb49f5ceb54fd2b4af0f7d2
Change-Id: I15d316f0fa244b69b3b8c629b8e8b8b2c26354e7