PPC: [runtime] Drop redundant %CharFromCode runtime entry.

PPC: [runtime] Drop redundant %CharFromCode runtime entry.

Port 2b4cb2a14011404e7d20341bdc91d890a4584a18

Original commit message:
    The %StringCharFromCode and %CharFromCode runtime function perform
    exactly the same task, so we need only one of them.

R=bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, dstence@us.ibm.com
BUG=

Committed: https://crrev.com/bdb04d5b8bba51ffaaeb229a2359bce503f2d1a2
Cr-Commit-Position: refs/heads/master@{#31904}

[MTBrandyberry, 2015-11-09 20:31:27]

The CQ bit was checked by mbrandy@us.ibm.com to run a CQ dry run

[commit-bot: I haz the power, 2015-11-09 20:31:43]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1429953005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1429953005/1

[michael_dawson, 2015-11-09 20:41:51]

On 2015/11/09 20:31:43, commit-bot: I haz the power wrote:
> Dry run: CQ is trying da patch. Follow status at
>  https://chromium-cq-status.appspot.com/patch-status/1429953005/1
> View timeline at
>  https://chromium-cq-status.appspot.com/patch-timeline/1429953005/1

lgtm

[commit-bot: I haz the power, 2015-11-09 21:00:55]

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

[commit-bot: I haz the power, 2015-11-09 21:00:56]

Dry run: This issue passed the CQ dry run.

[MTBrandyberry, 2015-11-09 21:01:06]

The CQ bit was checked by mbrandy@us.ibm.com

[commit-bot: I haz the power, 2015-11-09 21:01:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1429953005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1429953005/1

[commit-bot: I haz the power, 2015-11-09 21:02:33]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-09 21:02:55]

Patchset 1 (id:??) landed as
https://crrev.com/bdb04d5b8bba51ffaaeb229a2359bce503f2d1a2
Cr-Commit-Position: refs/heads/master@{#31904}