authfs: don't use crosvm_defaults

This is the final non-crosvm user of crosvm_defaults. The interesting
part of crosvm_defaults is the set of host targets it is enabled on, but
they mostly irrelevant for authfs, which is device-only.

Bug: 269356487
Test: m
Change-Id: I8b0da5bb1fa345475fcf703fc385e7f459158591
diff --git a/guest/authfs/Android.bp b/guest/authfs/Android.bp
index 28e0f4a..6c229b6 100644
--- a/guest/authfs/Android.bp
+++ b/guest/authfs/Android.bp
@@ -26,13 +26,12 @@
         "libthiserror",
     ],
     prefer_rlib: true,
-    target: {
-        darwin: {
+    multilib: {
+        lib32: {
             enabled: false,
         },
     },
     defaults: [
-        "crosvm_defaults",
         "avf_build_flags_rust",
     ],
 }
@@ -47,8 +46,4 @@
 rust_binary {
     name: "authfs",
     defaults: ["authfs_defaults"],
-    // //apex_available:platform is necessary here to counteract the
-    // com.android.virt in crosvm_defaults and make authfs available
-    // to the platform so it can be embedded in the microdroid image.
-    apex_available: ["//apex_available:platform"],
 }