Don't try to remove xcodebuild directory on Windows.

Don't try to remove xcodebuild directory on Windows.

make.py is a python script to be run *only* on Windows and thus
xcodebuild directory should not exist there. If we never create it on Windows,
then why should we try to remove something we don't create there?

R=epoger@google.com

Committed: https://code.google.com/p/skia/source/detail?r=14846

[tfarina, 2014-05-21 21:47:08]

Is this OK?

[epoger, 2014-05-21 21:55:29]

LGTM

(It's harmless either way)

[tfarina, 2014-05-22 15:54:12]

Committed patchset #1 manually as r14846 (presubmit successful).