Prepend 'call' to all non-cygwin commands to prevent incredibuild from aborting

Prepend 'call' to all non-cygwin commands to prevent incredibuild from aborting
the scripts early.

There are three cases:
  * Command is a batch file
  * Command is an exe/com
  * Command is a builtin (to cmd.exe).
  
In the first case, call will prevent the overall command action from aborting
when multiple commands are attached to the same file (look for 'and also' in the
msvs generator).

In the second, call does not change the exe's behavior

In the third case, call still performs the requested action correctly. This even
applies to the 'call' builtin, so, 'call call echo foo' is still correct.
Committed: https://code.google.com/p/gyp/source/detail?r=1469

[iannucci, 2012-08-14 19:48:51]

PTAL

[scottmg, 2012-08-14 19:56:13]

On 2012/08/14 19:48:51, iannucci wrote:
> PTAL

lgtm. It would be great to be able to add a test too. Perhaps you could prepend
something to the PATH that contains a python.bat (or whatever name) and verify
that the second step runs?

[iannucci, 2012-08-14 20:33:01]

On 2012/08/14 19:56:13, scottmg wrote:
> On 2012/08/14 19:48:51, iannucci wrote:
> > PTAL
> 
> lgtm. It would be great to be able to add a test too. Perhaps you could
prepend
> something to the PATH that contains a python.bat (or whatever name) and verify
> that the second step runs?

I thought about that, but AFAIK, the issue only happens when executing under
incredibuild, and not under msvs. I figured that the existing tests would be
enough to ensure that all the current functionality works as intended.

[scottmg, 2012-08-14 20:36:49]

On 2012/08/14 20:33:01, iannucci wrote:
> On 2012/08/14 19:56:13, scottmg wrote:
> > On 2012/08/14 19:48:51, iannucci wrote:
> > > PTAL
> > 
> > lgtm. It would be great to be able to add a test too. Perhaps you could
> prepend
> > something to the PATH that contains a python.bat (or whatever name) and
verify
> > that the second step runs?
> 
> I thought about that, but AFAIK, the issue only happens when executing under
> incredibuild, and not under msvs. I figured that the existing tests would be
> enough to ensure that all the current functionality works as intended.

OK.