message: [doc / util] Use comments to clarify time unit for int64_t type.
diff: @@ -43,7 +43,12 @@ int64_t GetTimeMicros();
  /** Returns the system time (not mockable) */
  int64_t GetSystemTimeInSeconds(); // Like GetTime(), but not mockable
  -/** For testing. Set e.g. with the setmocktime rpc, or -mocktime argument */
  +/**
  + * DEPRECATED
  + * Use SetMockTime with chrono type
  + *
  + * @param[in] nMockTimeIn Time in seconds.
  + */
  void SetMockTime(int64_t nMockTimeIn);
  /** For testing. Set e.g. with the setmocktime rpc, or -mocktime argument */
  