RFR: 8278766: Enable OpenJDK build support for reproducible jars and jmods using --date [v5]

[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 one additional commit 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>

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6878/files
  - new: https://git.openjdk.java.net/jdk/pull/6878/files/5fb4676b..add720cf

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6878&range=04
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6878&range=03-04

  Stats: 6 lines in 1 file changed: 4 ins; 0 del; 2 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