Skip building libfs_avb for darwin host

Bug: 112103720
Bug: 117960205
Test: build
Change-Id: If0bb8d15a62947e3af3bf02485a210715db90fdd
diff --git a/fs_mgr/libfs_avb/Android.bp b/fs_mgr/libfs_avb/Android.bp
index d22eceb..6f368e4 100644
--- a/fs_mgr/libfs_avb/Android.bp
+++ b/fs_mgr/libfs_avb/Android.bp
@@ -40,6 +40,11 @@
     header_libs: [
         "libbase_headers",
     ],
+    target: {
+        darwin: {
+            enabled: false,
+        },
+    },
 }
 
 cc_defaults {