Make libeigen apex_available for com.android.neuralnetworks

Test: -
Bug: 148593574
Change-Id: I3bc37477a7fda3dfe4f83ea5dfcf907d75e1e48a
diff --git a/Android.bp b/Android.bp
index ad2b8c5..7ccee6c 100644
--- a/Android.bp
+++ b/Android.bp
@@ -17,6 +17,11 @@
     export_include_dirs: ["."],
     vendor_available: true,
     host_supported: true,
+    apex_available: [
+        "com.android.neuralnetworks",
+        "test_com.android.neuralnetworks",
+	"//apex_available:platform",
+    ],
 }
 
 subdirs = ["blas"]