RFR: 8278766: Enable OpenJDK build support for reproducible jars and jmods using --date [v4]

[Andrew Leonard]

> If "reproducible build" is enabled, then utilize the new --date option in the building of jar's and jmods.
> Validating the boot jdk supports --date for the building of the jars.
> 
> Signed-off-by: Andrew Leonard <anleonar at redhat.com>

Andrew Leonard has updated the pull request incrementally with three additional commits since the last revision:

 - 8278766: Enable OpenJDK build support for reproducible jars and jmods using --date
   
   Signed-off-by: Andrew Leonard <anleonar at redhat.com>
 - 8278766: Enable OpenJDK build support for reproducible jars and jmods using --date
   
   Signed-off-by: Andrew Leonard <anleonar at redhat.com>
 - 8278766: Enable OpenJDK build support for reproducible jars and jmods using --date
   
   Signed-off-by: Andrew Leonard <anleonar at redhat.com>

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6878/files
  - new: https://git.openjdk.java.net/jdk/pull/6878/files/75c9d692..5fb4676b

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6878&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6878&range=02-03

  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6878.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6878/head:pull/6878

PR: https://git.openjdk.java.net/jdk/pull/6878