ninja: Enable deps mode on non-windows.
ninja: Enable deps mode on non-windows.

Windows will follow soon, if the new 1.3.0.git binary has worked well for a week
or so.

The Opera guys reported issues with deps mode when they tried it
(https://code.google.com/p/chromium/issues/detail?id=245034), but now they can
no longer repro. Maybe their issue was unrelated to deps mode.

Several folks have been using deps mode for a while without issues, so it should
work. If this does break your build somehow, please tell me about it.

No test since this should be no behavior change, it only makes things faster.

BUG=chromium:245034
Review URL: https://codereview.chromium.org/15713018/


witwall/gyp,witwall/gyp,witwall/gyp,witwall/gyp,witwall/gyp