This helps keep packages built on different machines have the
same datestamp, if started on the same time.
* tools/java 05ec511bbb...fd10821045 (1):
> build: use utc for build datestamp
* tools/jmx 48d37f3...d6225c5 (1):
> build: use utc for build datestamp
* tools/python3 c51db54...8a77e76 (1):
> build: use utc for build datestamp
[avi: commit own patches as this one requires excessive coordination
across submodules, for something quite innocuous]
Ref #9563 (doesn't really fix it, but helps a little)