libsnapshot: Don't package snapuserd.rc in /vendor/etc.

This is happening accidentally because of a bug in Soong. In the
meantime, add a separate snapuserd.vendor_ramdisk that does not have an
init_rc section.

Bug: N/A
Test: manual test
Change-Id: I9dcafb681f209932fa13c5c55478f0e486e53306
diff --git a/fs_mgr/libsnapshot/Android.bp b/fs_mgr/libsnapshot/Android.bp
index 34049d4..f441e02 100644
--- a/fs_mgr/libsnapshot/Android.bp
+++ b/fs_mgr/libsnapshot/Android.bp
@@ -439,7 +439,15 @@
     static_executable: true,
     system_shared_libs: [],
     ramdisk_available: true,
-    vendor_ramdisk_available: true,
+}
+
+cc_binary {
+    name: "snapuserd.vendor_ramdisk",
+    stem: "snapuserd",
+    defaults: ["snapuserd_defaults"],
+    static_executable: true,
+    system_shared_libs: [],
+    vendor_ramdisk: true,
 }
 
 cc_test {