Set apex_available of libbinder_headers

libbinder_headers was available to the APEXes via the hand-written
allowlist in build/soong/apex/apex.go. Trying to remove the allowlist by
adding apex_available property to libbinder_headers.

Bug: 150999716
Test: m
Change-Id: I9f1c6ec20d1c665ff148b3b78b7e01eebde5a229
diff --git a/libs/binder/Android.bp b/libs/binder/Android.bp
index 11b032b..7901f45 100644
--- a/libs/binder/Android.bp
+++ b/libs/binder/Android.bp
@@ -32,6 +32,11 @@
         "libcutils_headers",
         "libutils_headers",
     ],
+    apex_available: [
+        "//apex_available:platform",
+        "com.android.media",
+        "com.android.media.swcodec",
+    ],
     min_sdk_version: "29",
     target: {
         darwin: {