Add virtmanager to the virt APEX

We want to have virtmanager (and its dependencies) inside the APEX so
that they can be updated. This library is a dependency of the binary,
therefore it should also be marked as being available to the APEX.

Bug: 180297657
Test: com.android.virt
Change-Id: Id1234fc852f9fffdcf66f9a604a83b59f12d07ee
diff --git a/Android.bp b/Android.bp
index cf4bc93..1e6793a 100644
--- a/Android.bp
+++ b/Android.bp
@@ -10,4 +10,8 @@
         "default",
         "std",
     ],
+    apex_available: [
+        "//apex_available:platform",
+        "com.android.virt",
+    ],
 }