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.

Bug: 150999716
Test: m
Merged-In: I11a4e877ee27f7c55e2f00371c6fa58daedb1a9f
Change-Id: I11a4e877ee27f7c55e2f00371c6fa58daedb1a9f