Changing y2019 to absl::call_once()

Change-Id: Icb79ecc40c3505f7cfeb5d2a53e6d288a90b8a01
diff --git a/y2019/BUILD b/y2019/BUILD
index 792844f..04855d5 100644
--- a/y2019/BUILD
+++ b/y2019/BUILD
@@ -26,7 +26,7 @@
     ],
     visibility = ["//visibility:public"],
     deps = [
-        "//aos:once",
+        "@com_google_absl//absl/base",
         "//aos/logging",
         "//aos/mutex",
         "//aos/network:team_number",