MSVS 2008: Fix to ensure that actions are re-run when the command changes (v2)

MSVS 2008: Fix to ensure that actions are re-run when the command changes

There was some code to re-run an action, but it only worked if the
command change came from a change to a .gyp file, and only if the
"inputs" list was empty.  It didn't work if the command change came
from a change to a .gypi file.

To fix this, we create "*.gypcmd" stamp files that contain the command
text, and when the command text changes we update these files'
timestamps.

If a Gyp target contains multiple actions, this should rerun only the
actions that changed.

BUG=http://code.google.com/p/gyp/issues/detail?id=262
TEST=test/actions-args-change

Committed: https://code.google.com/p/gyp/source/detail?r=1362

[Mark Seaborn, 2012-05-04 21:01:51]

This replaces http://codereview.chromium.org/10306013/ and fixes the problem
Ryan raised about unnecessary rebuilds.  It turned out that the more
fine-grained version was easy enough to do.

[jeanluc1, 2012-05-04 22:30:14]

lgtm

[Ryan Sleevi, 2012-05-04 22:45:17]

Thanks Mark! I reviewed-for-approach and I think this will be great. I don't
know if it will wholly fix the MSVC 2008 issues for compiling .cc files, meaning
it won't help all of the WebKit woes, but looks fine for actions.

[M-A Ruel, 2012-05-16 10:53:33]

On 2012/05/04 22:45:17, Ryan Sleevi wrote:
> Thanks Mark! I reviewed-for-approach and I think this will be great. I don't
> know if it will wholly fix the MSVC 2008 issues for compiling .cc files,
meaning
> it won't help all of the WebKit woes, but looks fine for actions.

This seems to have killed the windows try slaves, as a random example;
http://build.chromium.org/p/tryserver.chromium/builders/win_rel/builds/29535/...
These gypmd are removed at each try job. This seems to have turned every windows
try jobs into clobber compile.