[8u] RFR 8177809: File.lastModified() is losing milliseconds (always ends in 000)

[Zhengyu Gu]

I would like to backport this patch to 8u for parity with Oracle 8u301.

The original bug: https://bugs.openjdk.java.net/browse/JDK-8177809
The original patch: 
http://hg.openjdk.java.net/jdk10/jdk10/jdk/rev/8e2030e03a61

The original patch does not apply cleanly. The only conflict was 
copyright year line of UnixFileSystem_md.c

8u webrev: http://cr.openjdk.java.net/~zgu/JDK-8177809-8u/webrev.00/

Test:
   Passed test in patch.

Thanks,

-Zhengyu