_XcodeVersion: return CLT version as appropriate

_XcodeVersion: return CLT version as appropriate

If Xcode isn't installed passing the CLT version is the next best bet.
This ports the CLT version function from Homebrew, and calls it if
xcodebuild fails to run.

BUG=code.google.com/p/gyp/issues/detail?id=292

r1826

[mistydemeo, 2013-12-19 16:35:08]

This patch cleans up an additional couple of xcodebuild usages in
xcode_emulation (refs https://codereview.chromium.org/102733012/). This adds a
new _CLTVersion() method to check the version of the CLT on the system. If no
Xcode version is found, it returns the CLT version instead. This resolves some
additional issues that could come up for CLT-only users.

(I still plan to review the issues caused by the previous commit, either tonight
or on the weekend. Sorry I haven't had the chance yet.)

[Nico, 2013-12-19 17:17:58]

On 2013/12/19 16:35:08, mistydemeo wrote:
> This patch cleans up an additional couple of xcodebuild usages in
> xcode_emulation (refs https://codereview.chromium.org/102733012/). This adds a
> new _CLTVersion() method to check the version of the CLT on the system. If no
> Xcode version is found, it returns the CLT version instead. This resolves some
> additional issues that could come up for CLT-only users.
> 
> (I still plan to review the issues caused by the previous commit, either
tonight
> or on the weekend. Sorry I haven't had the chance yet.)

Ok. I'll revert that change for now then, as the red bots are preventing us from
updating gyp in chromium. Thanks for looking at this!

[mistydemeo, 2013-12-24 21:16:29]

On 2013/12/19 17:17:58, Nico wrote:
> Ok. I'll revert that change for now then, as the red bots are preventing us
from
> updating gyp in chromium. Thanks for looking at this!

Now that the other change has landed, I've rebased this on top of master. Tests
are passing. This is also needed for CLT users to be able to use gyp.

[Nico, 2013-12-26 17:54:42]

lgtm

Try jobs at https://codereview.chromium.org/106293003 , if they come back green
I'll land this.

(Sorry about the delay!)

[Nico, 2013-12-26 18:09:23]

r1826

[mistydemeo, 2013-12-26 21:24:03]

Thank you!