Disable authfs for darwin host

Bug: 177260439
Test: m authfs
Change-Id: I8a9a7a52a6ab973687aba8ed11ff2d3eddba76ad
diff --git a/authfs/Android.bp b/authfs/Android.bp
index f9fdd1f..104221e 100644
--- a/authfs/Android.bp
+++ b/authfs/Android.bp
@@ -15,6 +15,11 @@
         "libthiserror",
     ],
     host_supported: true,
+    target: {
+        darwin: {
+            enabled: false,
+        },
+    },
     shared_libs: ["libcrypto"],
     clippy_lints: "android",
     defaults: ["crosvm_defaults"],