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

Review URL: https://codereview.chromium.org/299443005

git-svn-id: http://skia.googlecode.com/svn/trunk@14846 2bbb7eff-a529-9590-31e7-b0007b416f81

make.py

@@ -51,8 +51,6 @@ def MakeClean():
     """Cross-platform "make clean" operation."""
     cd(SCRIPT_DIR)
     rmtree(OUT_SUBDIR)
-    # clean up the directory that XCode (on Mac) creates
-    rmtree('xcodebuild')
 
 
 def CheckWindowsEnvironment():