Added support of the PlatformToolset property to Gyp (MSBuild only).

Added support of the PlatformToolset property to Gyp (MSBuild only). This property provides a clean way of specifying the desired version of SDK to be used to build a particular project.

The desired version of the toolset can be specified in target's specification as 'msbuild_toolset'. For instance the following can be added to 'target_defaults':

'conditions': [
  ...
  ['OS=="win"', {
    'msbuild_toolset': 'Windows7.1SDK',
  }],
  ...

'msbuild_toolset' has effect only when emitting MSBuild projects. When 'msbuild_toolset' is not specified, PlatformToolset is not emitted letting MSBuild to choose the default platform toolset.

Contributed by alexeypa@chromium.org

[alexeypa (please no reviews), 2012-02-14 20:44:50]

I figured it'll raise changes of this CL to be reviewed if I pick somebody. I
pick the reviewer of the last change that affected msvs.py.

Here is some background information about the CL:
http://groups.google.com/group/gyp-developer/browse_thread/thread/a087f3c7cf4...

[alexeypa (please no reviews), 2012-02-14 20:47:45]

/My previous e-mail bounced . Resending.../

I figured it'll raise changes of this CL to be reviewed if I pick somebody. I
pick the reviewer of the last change that affected msvs.py.

Here is some background information about the CL:
http://groups.google.com/group/gyp-developer/browse_thread/thread/a087f3c7cf4...

[bradn, 2012-02-15 06:23:17]

https://chromiumcodereview.appspot.com/9390017/diff/1/pylib/gyp/generator/msv...
File pylib/gyp/generator/msvs.py (right):

https://chromiumcodereview.appspot.com/9390017/diff/1/pylib/gyp/generator/msv...
pylib/gyp/generator/msvs.py:2844: msvs_toolset =
generator_flags.get('msvs_toolset', 'auto')
Rather than having this be a generator flag, could we base it on something in
spec/configuration? So it can be configured in common.gypi ? That way everyone
doesn't need to tweak their environment. If its set via a gyp variable with % it
can still be overridden as needed.

Little rusty on the scheme, I realize msbuild_settings clobbers msvs_settings,
so we probably can't add it to msbuild_settings?

[alexeypa (please no reviews), 2012-02-17 18:11:40]

/Sorry for the delay. I had to educate myself how Gyp processes target
configurations./

Here is the version that allows choosing the desired toolset by setting
'msbuild_toolset' in target's specification. PTAL. Thanks.

https://chromiumcodereview.appspot.com/9390017/diff/1/pylib/gyp/generator/msv...
File pylib/gyp/generator/msvs.py (right):

https://chromiumcodereview.appspot.com/9390017/diff/1/pylib/gyp/generator/msv...
pylib/gyp/generator/msvs.py:2844: msvs_toolset =
generator_flags.get('msvs_toolset', 'auto')
On 2012/02/15 06:23:17, bradn wrote:
> Rather than having this be a generator flag, could we base it on something in
> spec/configuration? So it can be configured in common.gypi ? That way everyone
> doesn't need to tweak their environment. If its set via a gyp variable with %
it
> can still be overridden as needed.
> 
> Little rusty on the scheme, I realize msbuild_settings clobbers msvs_settings,
> so we probably can't add it to msbuild_settings?

This certainly makes sense. Take a look at the updated CL.

[bradn, 2012-02-17 18:16:35]

lgtm

[alexeypa (please no reviews), 2012-02-17 18:30:19]

On 2012/02/17 18:16:35, bradn wrote:
> lgtm

I'm not a committer yet. Could you please commit it for me? Thanks.

[alexeypa (please no reviews), 2012-02-22 17:51:42]

On 2012/02/17 18:30:19, alexeypa wrote:
> On 2012/02/17 18:16:35, bradn wrote:
> > lgtm
> 
> I'm not a committer yet. Could you please commit it for me? Thanks.

Ping. Could you please help me checking this CL in?

[scottmg, 2012-02-22 18:15:31]

On 2012/02/22 17:51:42, alexeypa wrote:
> On 2012/02/17 18:30:19, alexeypa wrote:
> > On 2012/02/17 18:16:35, bradn wrote:
> > > lgtm
> > 
> > I'm not a committer yet. Could you please commit it for me? Thanks.
> 
> Ping. Could you please help me checking this CL in?

Committed at r1228.

[scottmg, 2012-02-22 22:55:20]

On 2012/02/22 18:15:31, scottmg wrote:
> On 2012/02/22 17:51:42, alexeypa wrote:
> > On 2012/02/17 18:30:19, alexeypa wrote:
> > > On 2012/02/17 18:16:35, bradn wrote:
> > > > lgtm
> > > 
> > > I'm not a committer yet. Could you please commit it for me? Thanks.
> > 
> > Ping. Could you please help me checking this CL in?
> 
> Committed at r1228.

Recommitted after revert at r1230.