Add apex_available to libnetutils

The library is included by the tethering module, and was allowlisted
for compatibility purposes, but needs to have the rule applied.

Bug: 171540887
Test: m
Change-Id: Ic02c559d6e82fb41c33ba723bd06ef708e7baaa9
diff --git a/libnetutils/Android.bp b/libnetutils/Android.bp
index 65371fa..eec2415 100644
--- a/libnetutils/Android.bp
+++ b/libnetutils/Android.bp
@@ -21,6 +21,11 @@
     cflags: ["-Werror"],
 
     export_include_dirs: ["include"],
+    // TODO: remove connectivity module dependency, or have this lib build against the ndk
+    apex_available: [
+        "//apex_available:platform",
+        "com.android.tethering",
+    ],
 }
 
 cc_library_static {