Improve watchdog logging

- Include start time in overdue report.
- Make extent of report clearer.

Test: watch logcat
Change-Id: I9db6462d8a6ce0754edac9f41427f351aa756c6c
diff --git a/keystore2/watchdog/Android.bp b/keystore2/watchdog/Android.bp
index 5074388..9a99f10 100644
--- a/keystore2/watchdog/Android.bp
+++ b/keystore2/watchdog/Android.bp
@@ -26,6 +26,7 @@
     crate_name: "watchdog_rs",
     srcs: ["src/lib.rs"],
     rustlibs: [
+        "libchrono",
         "liblog_rust",
     ],
 }