Move safe_strerror to posix directory and the base namespace

Move safe_strerror to posix directory and the base namespace.

Since this is a wrapper around a posix thing that doesn't fall under any other categories, the posix directory is probably the best place.

Committed: https://crrev.com/6ee6fd6efabf8b87324d0b233ea2332c4a0e1642
Cr-Commit-Position: refs/heads/master@{#333524}

[brettw, 2015-06-04 20:59:51]

The CQ bit was checked by brettw@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-04 21:01:37]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1160373004/1

[commit-bot: I haz the power, 2015-06-04 21:21:11]

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

[commit-bot: I haz the power, 2015-06-04 21:21:13]

Dry run: Try jobs failed on following builders:
  linux_chromium_gn_dbg on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  ios_dbg_simulator_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_dbg_simulator...)
  ios_rel_device_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_rel_device_ni...)

[brettw, 2015-06-04 21:23:22]

The CQ bit was checked by brettw@chromium.org to run a CQ dry run

[brettw, 2015-06-04 21:24:22]

brettw@chromium.org changed reviewers:
+ danakj@chromium.org

[commit-bot: I haz the power, 2015-06-04 21:24:51]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1160373004/20001

[commit-bot: I haz the power, 2015-06-04 21:39:13]

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

[commit-bot: I haz the power, 2015-06-04 21:39:15]

Dry run: Try jobs failed on following builders:
  android_chromium_gn_compile_dbg on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/android_chromiu...)
  android_chromium_gn_compile_rel on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/android_chromiu...)

[brettw, 2015-06-05 16:45:36]

The CQ bit was checked by brettw@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-05 16:45:57]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1160373004/40001

[commit-bot: I haz the power, 2015-06-05 17:51:31]

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

[commit-bot: I haz the power, 2015-06-05 17:51:33]

Dry run: This issue passed the CQ dry run.

[brettw, 2015-06-09 16:53:17]

Whoops, forgot to actually send mail.

[brettw, 2015-06-09 16:54:07]

The CQ bit was checked by brettw@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-09 16:54:19]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1160373004/60001

[danakj, 2015-06-09 17:23:04]

LGTM

[brettw, 2015-06-09 17:25:31]

The CQ bit was unchecked by brettw@chromium.org

[brettw, 2015-06-09 17:25:35]

The CQ bit was checked by brettw@chromium.org

[commit-bot: I haz the power, 2015-06-09 17:26:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1160373004/60001

[commit-bot: I haz the power, 2015-06-09 18:05:36]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-06-09 18:06:26]

Patchset 4 (id:??) landed as
https://crrev.com/6ee6fd6efabf8b87324d0b233ea2332c4a0e1642
Cr-Commit-Position: refs/heads/master@{#333524}