Automatically download gold plugin for cfi builds.

Automatically download gold plugin for cfi builds.

BUG=chromium:515782
LOG=n
NOTRY=true

Committed: https://crrev.com/c8dbd2c477c47a34593a0e7deee55915425b4ac2
Cr-Commit-Position: refs/heads/master@{#30556}

[Michael Achenbach, 2015-09-03 11:57:17]

machenbach@chromium.org changed reviewers:
+ bmeurer@chromium.org

[Michael Achenbach, 2015-09-03 11:57:18]

PTAL. Now the gold plugin will be downloaded automatically if cfi is specified.
The up-to-date check is pinned to clang's version.

A bit hacky - nicer would be if the gold plugin had its own stamp and version
file - or an md5 hash checked in to which it could be compared, to avoid
unnecessary downloads.

[Benedikt Meurer, 2015-09-03 11:57:52]

lgtm

[Michael Achenbach, 2015-09-03 12:13:17]

The CQ bit was checked by machenbach@chromium.org

[commit-bot: I haz the power, 2015-09-03 12:13:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1303183005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1303183005/1

[commit-bot: I haz the power, 2015-09-03 12:15:06]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-03 12:15:23]

Patchset 1 (id:??) landed as
https://crrev.com/c8dbd2c477c47a34593a0e7deee55915425b4ac2
Cr-Commit-Position: refs/heads/master@{#30556}

[Michael Achenbach, 2015-09-03 12:50:14]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1329653004/ by machenbach@chromium.org.

The reason for reverting is: Breaks windows..