GN: Use interface jars in the classpath to speed up compiling (a little)

GN: Use interface jars in the classpath to speed up compiling (a little)

Rebuilding chrome_java before change:
real    1m0.108s
user    7m44.609s
sys     0m27.630s

Rebuilding chrome_java after change:
real    0m57.893s
user    7m22.493s
sys     0m21.224s

BUG=527632
Committed: https://crrev.com/6d6c9ac82e8f06abb047501d37b95cae145a727c
Cr-Commit-Position: refs/heads/master@{#347405}

[agrieve, 2015-09-03 19:59:48]

agrieve@chromium.org changed reviewers:
+ dpranke@chromium.org

[Dirk Pranke, 2015-09-03 20:12:23]

lgtm

[Dirk Pranke, 2015-09-03 20:12:30]

lgtm

[agrieve, 2015-09-04 13:55:39]

The CQ bit was checked by agrieve@chromium.org

[commit-bot: I haz the power, 2015-09-04 13:55:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1328823002/50001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1328823002/50001

[commit-bot: I haz the power, 2015-09-04 14:57:42]

Committed patchset #4 (id:50001)

[commit-bot: I haz the power, 2015-09-04 14:58:22]

Patchset 4 (id:??) landed as
https://crrev.com/6d6c9ac82e8f06abb047501d37b95cae145a727c
Cr-Commit-Position: refs/heads/master@{#347405}