Remove redundant source position information in RelocInfo

Remove redundant source position information in RelocInfo

Previously, emitting two more more unique source positions at the same pc would
generate two or more RelocInfo entries. Now, only the last emitted source
position for any pc is added to the RelocInfo.

Committed: https://crrev.com/e87c0bac3540b8ba24b02dfcc65af485f4020157
Cr-Commit-Position: refs/heads/master@{#26608}

[danno, 2015-02-06 16:36:13]

danno@chromium.org changed reviewers:
+ yangguo@chromium.org

[danno, 2015-02-06 16:36:14]

PTAL

[Yang, 2015-02-11 15:29:30]

On 2015/02/06 16:36:14, danno wrote:
> PTAL

lgtm.

[danno, 2015-02-12 11:52:55]

The CQ bit was checked by danno@chromium.org

[commit-bot: I haz the power, 2015-02-12 11:53:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/908443002/80001

[commit-bot: I haz the power, 2015-02-12 12:15:21]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2015-02-12 12:15:41]

Patchset 5 (id:??) landed as
https://crrev.com/e87c0bac3540b8ba24b02dfcc65af485f4020157
Cr-Commit-Position: refs/heads/master@{#26608}