Fix "No file_contexts" warning

Fixed by Loading the file_contexts specified in libselinux, whereas
previously recovery loaded /file_contexts which no longer exists.

Bug: 62587423
Test: build and flash recovery on Angler. Warning is gone.
Test: Wipe data and cache.
Test: sideload OTA
Change-Id: I11581c878b860ac5f412e6e8e7acde811f37870f
(cherry picked from commit 2330dd8733ce0b207058e3003a3b1efebc022394)
diff --git a/updater/updater.cpp b/updater/updater.cpp
index c09e267..f3e2820 100644
--- a/updater/updater.cpp
+++ b/updater/updater.cpp
@@ -25,6 +25,7 @@
 
 #include <android-base/logging.h>
 #include <android-base/strings.h>
+#include <selinux/android.h>
 #include <selinux/label.h>
 #include <selinux/selinux.h>
 #include <ziparchive/zip_archive.h>
@@ -139,9 +140,8 @@
     return 6;
   }
 
-  struct selinux_opt seopts[] = { { SELABEL_OPT_PATH, "/file_contexts" } };
-
-  sehandle = selabel_open(SELABEL_CTX_FILE, seopts, 1);
+  sehandle = selinux_android_file_context_handle();
+  selinux_android_set_sehandle(sehandle);
 
   if (!sehandle) {
     fprintf(cmd_pipe, "ui_print Warning: No file_contexts\n");