Revert 194740 "Explicitly pass "--diff-cmd diff" to "svn diff", ..."

Revert 194740 "Explicitly pass "--diff-cmd diff" to "svn diff", ..."

On Windows, I got the following error:
f:\src\chrome2\src>gcl commit n3d2
Loaded authentication cookies from C:\Users\jabdelmalek/.codereview_upload_cookies
Running presubmit commit checks ...
  checking owners took a long time: 906ms
Got an exception
Command svn diff --diff-cmd diff --config-dir c:\users\jabdel~1\appdata\local\temp\tmpu7bui5 content\browser\web_content
s\web_contents_impl.cc returned non-zero exit status 1 in f:\src\chrome2\src
Index: content/browser/web_contents/web_contents_impl.cc
===================================================================

svn: Can't start process 'diff': The system cannot find the file specified.

> Explicitly pass "--diff-cmd diff" to "svn diff", for users who have set some other diff tool.
> 
> Review URL: https://chromiumcodereview.appspot.com/14130006

TBR=pkasting@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=194945

[Peter Kasting, 2013-04-18 18:34:55]

LGTM, thanks; this was the wrong way to implement this.