Move loader stub libraries out of //build/config/linux

Move loader stub libraries out of //build/config/linux

The //build/config/linux library defined a number of targets
built through the generate_library_loader target. All of these
are fairly chrome-specific, so having them defined in the
//build/config/linux file made it harder to reuse that file
in non-chrome GN builds (like native_client).

This CL moves the targets out to a new //build/linux directory
and updates the callers accordingly.

R=brettw@chromium.org
BUG=

Committed: https://crrev.com/ad0c1f495eca0968601ea74254b86fb91d412eb0
Cr-Commit-Position: refs/heads/master@{#346242}

[brettw, 2015-08-28 17:46:11]

lgtm

[Dirk Pranke, 2015-08-28 18:12:30]

The CQ bit was checked by dpranke@chromium.org

[commit-bot: I haz the power, 2015-08-28 18:13:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1314163005/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1314163005/20001

[commit-bot: I haz the power, 2015-08-28 18:18:53]

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

[commit-bot: I haz the power, 2015-08-28 18:18:54]

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

[Dirk Pranke, 2015-08-28 18:58:16]

The CQ bit was checked by dpranke@chromium.org

[Dirk Pranke, 2015-08-28 18:58:16]

The patchset sent to the CQ was uploaded after l-g-t-m from brettw@chromium.org
Link to the patchset: https://codereview.chromium.org/1314163005/#ps40001
(title: "fix exec_script() whitelist")

[commit-bot: I haz the power, 2015-08-28 18:58:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1314163005/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1314163005/40001

[commit-bot: I haz the power, 2015-08-28 19:05:01]

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

[commit-bot: I haz the power, 2015-08-28 19:05:02]

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

[Dirk Pranke, 2015-08-28 20:42:16]

The CQ bit was checked by dpranke@chromium.org

[Dirk Pranke, 2015-08-28 20:42:16]

The patchset sent to the CQ was uploaded after l-g-t-m from brettw@chromium.org
Link to the patchset: https://codereview.chromium.org/1314163005/#ps60001
(title: "fix libbrl references")

[commit-bot: I haz the power, 2015-08-28 20:42:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1314163005/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1314163005/60001

[commit-bot: I haz the power, 2015-08-28 21:48:09]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-08-28 21:49:21]

Patchset 4 (id:??) landed as
https://crrev.com/ad0c1f495eca0968601ea74254b86fb91d412eb0
Cr-Commit-Position: refs/heads/master@{#346242}