Fixes for 32-bit official GN build.

Fixes for 32-bit official GN build.

Uses the host toolchain for the dump symbol and stack walk utilities.

Remove the dummy nacl target when nacl is disabled. Previously there was a dummy nacl target but no dummy nacl_helper target. They should be consistent. It turns out we use neither when nacl is disabled, so I removed the existing one.

Unrelated: Update GN quick start with a link to the new sites page I made
for build arguments.

Committed: https://crrev.com/314880aa20d7e71bc01515afa7b9c82e763f4218
Cr-Commit-Position: refs/heads/master@{#348477}

[brettw, 2015-09-11 17:28:26]

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

[brettw, 2015-09-11 17:28:32]

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

[commit-bot: I haz the power, 2015-09-11 17:29:29]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1339653004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1339653004/1

[commit-bot: I haz the power, 2015-09-11 18:01:16]

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

[commit-bot: I haz the power, 2015-09-11 18:01:17]

Dry run: This issue passed the CQ dry run.

[Dirk Pranke, 2015-09-11 19:49:25]

lgtm

[brettw, 2015-09-11 20:02:47]

The CQ bit was checked by brettw@chromium.org

[commit-bot: I haz the power, 2015-09-11 20:03:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1339653004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1339653004/1

[commit-bot: I haz the power, 2015-09-11 20:09:37]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-11 20:10:17]

Patchset 1 (id:??) landed as
https://crrev.com/314880aa20d7e71bc01515afa7b9c82e763f4218
Cr-Commit-Position: refs/heads/master@{#348477}

[commit-bot: I haz the power, 2015-09-23 12:25:57]

Patchset 1 (id:??) landed as
https://crrev.com/314880aa20d7e71bc01515afa7b9c82e763f4218
Cr-Commit-Position: refs/heads/master@{#348477}