Make libloading available to product and vendor

Bug: 270690570

Test: mma in external/rust/crates
Change-Id: I260a11cc265ee37af8aefdafe2d3452c8f37134f
diff --git a/Android.bp b/Android.bp
index 62f030e..4c7c2ac 100644
--- a/Android.bp
+++ b/Android.bp
@@ -33,5 +33,6 @@
         "//apex_available:platform",
         "com.android.virt",
     ],
+    product_available: true,
     vendor_available: true,
 }