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: cherry-pick from AOSP

Bug: 150999716
Test: m
Merged-In: I8fd2a3c9b69454c6018c72f5198898bc90dc4d0d
(cherry picked from commit 937b4bf1)
Change-Id: I8fd2a3c9b69454c6018c72f5198898bc90dc4d0d