Make libnativehelper_header_only APEX available

This enables libstats_jni to use ScopedLocalRef.

Bug: 157711673
Test: m nothing (with this topic)
Change-Id: I98651c7cf07fc3b89f2ee46d5a7a019cee329abf
diff --git a/Android.bp b/Android.bp
index ca62873..46f46f8 100644
--- a/Android.bp
+++ b/Android.bp
@@ -43,8 +43,7 @@
 
     apex_available: [
         "//apex_available:platform",
-        "com.android.art.debug",
-        "com.android.art.release",
+        "//apex_available:anyapex",
     ],
 }
 
@@ -94,6 +93,7 @@
             enabled: true,
         },
     },
+    // Please avoid adding APEX dependencies on this for R (b/157711673).
     apex_available: [
         "com.android.art.release",
         "com.android.art.debug",