Change skia_target_arch != arm to skia_target_arch == x86 in gyp files

BUG= http://code.google.com/p/skia/issues/detail?id=478

[bsalomon, 2012-03-06 20:26:25]

This is an improvement but still leaves a lot to be desired:

1) It'd be better for the default to infer that the target arch matches the
machine performing the build rather than x86.

2) When the underlying build system supports a flag to cross compile we should
use skia_target_arch to set that flag.

3) There is no distinction between x86 and x86-64.

[TomH, 2012-03-06 20:28:19]

<shrug> LGTM, but I don't know enough to evaluate it. epoger@?

[DerekS, 2012-03-06 20:29:16]

On 2012/03/06 20:28:19, TomH wrote:
> <shrug> LGTM, but I don't know enough to evaluate it. epoger@?

LGTM. I agree it can be improved beyond this but this is much better than what
we have now.

[bsalomon, 2012-03-06 20:29:22]

Adding epoger.

The motivation is to stop assuming !arm == x86.

[epoger, 2012-03-06 20:36:37]

LGTM

I agree that this is a step in the right direction.

Please associate this change with
http://code.google.com/p/skia/issues/detail?id=478 ('gyp cleanup: list valid
skia_target_arch values, and set to 'x86' by default'), and weigh in there with
thoughts on other areas where we need to clean this up.  

For instance, do we still need to check skia_target_arch before setting the
-msse2 compiler flag?

[bsalomon, 2012-03-06 21:43:39]

Closed with r3322