Make libselinux_bindgen available to the virt APEX

Bug: 204852957
Test: m
Change-Id: I652c42c38a568883bb05d7756e9012adc12b4194
diff --git a/libselinux/Android.bp b/libselinux/Android.bp
index 5fb2deb..6275b41 100644
--- a/libselinux/Android.bp
+++ b/libselinux/Android.bp
@@ -331,6 +331,11 @@
 
     // This is mainly to run layout tests for generated bindings on the host.
     host_supported: true,
+
+    apex_available: [
+        "com.android.virt",
+        "//apex_available:platform",
+    ],
 }
 
 rust_test {