Make v8_target_arch a GN declare_arg().

Make v8_target_arch a GN declare_arg().

There are bots on the chromium.lkgr waterfall that need to
be able to set v8_target_arch to "arm" while the rest of
the target build is "x86". This CL makes that argument
a declare_arg(), so that we can do that.

R=machenbach@chromium.org
BUG=605732

[Dirk Pranke, 2016-05-24 01:55:46]

Description was changed from

==========
Make v8_target_cpu a GN declare_arg().

There are bots on the chromium.lkgr waterfall that need to
be able to set v8_target_cpu to "arm" while the rest of
the target build is "x86". This CL makes that argument
a declare_arg(), so that we can do that.

R=machenbach@chromium.org
BUG=605732
==========

to

==========
Make v8_target_arch a GN declare_arg().

There are bots on the chromium.lkgr waterfall that need to
be able to set v8_target_arch to "arm" while the rest of
the target build is "x86". This CL makes that argument
a declare_arg(), so that we can do that.

R=machenbach@chromium.org
BUG=605732
==========

[Michael Achenbach, 2016-05-24 06:39:33]

lgtm with comment

https://codereview.chromium.org/2006163004/diff/1/BUILD.gn
File BUILD.gn (right):

https://codereview.chromium.org/2006163004/diff/1/BUILD.gn#newcode77
BUILD.gn:77: v8_target_arch = ""
I've recently added this to v8's overrides:
https://code.google.com/p/chromium/codesearch#chromium/src/v8/build_overrides...

It should be removed there now.

I'm not so sure about the documentation. This seems sanitizer specific and
should go to the is_msan condition below. As main docu maybe:
"V8 generates code for this architecture. If v8_target_arch differs from
target_arch, a simulator will be run."

[Michael Achenbach, 2016-05-24 18:26:03]

FYI: Landed this now: https://codereview.chromium.org/2007843002/

[Dirk Pranke, 2016-05-24 18:41:05]

On 2016/05/24 18:26:03, Michael Achenbach (slow) wrote:
> FYI: Landed this now: https://codereview.chromium.org/2007843002/

Yup, closing this CL in favor of https://codereview.chromium.org/2007843002/ and
https://codereview.chromium.org/2006213002/ .