CachedDateFormat: Correct fix for handling ts with 654 as ms part

The previous commit [1] tried to fix the issue that findMillisecondStart
does not work correctly when the millisecond part of the timestamp is
654 ms. However, it only fixed the issue for the special case when the
millisecond part was 654 and the microsecond part was 0, even though the
microseconds should not matter.

Fix this by comparing in milliseconds instead of in microseconds.

Fixes LOGCXX-506.

[1]: 396c8abfe92136db6ba2453bf804ba8ca48a923d
2 files changed