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 internal

Bug: 150999716
Test: m
Merged-In: If64eff62b9e93af95089e5010c30eb586673b92e
(cherry picked from commit 693a7214d63ff0a2190b9401dacaccd995b07af7)
Change-Id: If64eff62b9e93af95089e5010c30eb586673b92e
diff --git a/libc/Android.bp b/libc/Android.bp
index 9a01720..e6b70b5 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -1779,6 +1779,13 @@
     system_shared_libs: [],
     stl: "none",
     sdk_version: "current",
+
+    apex_available: [
+        "//apex_available:platform",
+        "com.android.runtime",
+        "com.android.art.release", // from libdexfile_external
+        "com.android.art.debug", // from libdexfile_external
+    ],
 }
 
 // libc_headers for libasync_safe and libpropertyinfoparser