Add -bootclasspath argument to javac.

Add -bootclasspath argument to javac.

This silences the warning "bootstrap class path not set in conjunction
with -source 1.7" when building with OpenJDK 1.8.

The multiple_proguards test was removed as javac will now catch the use
of host packages that do not exist on Android.

BUG=

Committed: https://crrev.com/718538ef3a6e6f7104101ef37502052c88c5641c
Cr-Commit-Position: refs/heads/master@{#337805}

[Fredrik Öhrn, 2015-07-03 13:22:57]

ohrn@opera.com changed reviewers:
+ cjhopman@chromium.org, dpranke@chromium.org

[Fredrik Öhrn, 2015-07-03 13:22:58]

+cjhopman looks like you review these files a lot
+dpranke for the .gni file

[Dirk Pranke, 2015-07-03 19:24:50]

internal_rules.gni lgtm.

[Fredrik Öhrn, 2015-07-07 15:03:39]

On 2015/07/03 19:24:50, Dirk Pranke wrote:
> internal_rules.gni lgtm.

'cept I forgot to rebase the path as usual, patch updated.

[cjhopman, 2015-07-07 18:42:30]

lgtm

[Fredrik Öhrn, 2015-07-08 08:27:07]

The CQ bit was checked by ohrn@opera.com

[Fredrik Öhrn, 2015-07-08 08:27:07]

The patchset sent to the CQ was uploaded after l-g-t-m from dpranke@chromium.org
Link to the patchset: https://codereview.chromium.org/1213433007/#ps20001
(title: "Rebase path")

[commit-bot: I haz the power, 2015-07-08 08:27:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1213433007/20001

[commit-bot: I haz the power, 2015-07-08 10:57:20]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-07-08 10:57:21]

Try jobs failed on following builders:
  linux_android_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_android_r...)

[Fredrik Öhrn, 2015-07-08 13:04:56]

The CQ bit was checked by ohrn@opera.com

[commit-bot: I haz the power, 2015-07-08 13:05:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1213433007/20001

[commit-bot: I haz the power, 2015-07-08 13:09:14]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-07-08 13:10:19]

Patchset 2 (id:??) landed as
https://crrev.com/718538ef3a6e6f7104101ef37502052c88c5641c
Cr-Commit-Position: refs/heads/master@{#337805}