Adds -f when rm'ing pyc files

Without this I get prompted if I really want to remote the file.

BUG=none
TEST=none

Review URL: https://codereview.chromium.org/1332303003

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@296651 0039d316-1c4b-4281-b951-d872f2087c98

update_depot_tools

@@ -152,7 +152,7 @@ then
   fi
 fi
 
-find "$base_dir" -iname "*.pyc" -exec rm {} \;
+find "$base_dir" -iname "*.pyc" -exec rm -f {} \;
 
 # Initialize/update virtualenv.
 cd $base_dir