Fix GYP cross-compilation issue w/ build_utf8_validator_tables.

Fix GYP cross-compilation issue w/ build_utf8_validator_tables.

I think, when explicitly declaring a dependency on a target
(like gn_all does on build_utf8_validator_tables), if the target
is unconditionally only built in the host toolset, the dependency
needs to also say that; my initial version of the dependency did
not do that, leading gyp_chromium to fail in obscure ways.

R=thakis@chromium.org
BUG=465198
Committed: https://crrev.com/3b02cf778cdb3066ed3cbb9b2d70413a1577033e
Cr-Commit-Position: refs/heads/master@{#319666}

[Nico, 2015-03-09 05:41:02]

lgtm, this is conceptually correct. (I didn't verify that these two targets
indeed say 'toolsets':  ['host'], I trust you checked that.)

In non-cross builds, the #host gets stripped here
https://code.google.com/p/chromium/codesearch#chromium/src/tools/gyp/pylib/gy...
and that's why things should work in non-cross configs too.

[Dirk Pranke, 2015-03-09 16:34:26]

The CQ bit was checked by dpranke@chromium.org

[commit-bot: I haz the power, 2015-03-09 16:35:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/990093002/1

[commit-bot: I haz the power, 2015-03-09 17:20:13]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-09 17:21:24]

Patchset 1 (id:??) landed as
https://crrev.com/3b02cf778cdb3066ed3cbb9b2d70413a1577033e
Cr-Commit-Position: refs/heads/master@{#319666}