Clang-on-Windows update script: track HEAD

During this phase we want to use the latest and greatest Clang,
and get notified about build regressions as soon as possible.

BUG=82385
R=rnk@chromium.org

Review URL: https://codereview.chromium.org/177533015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253202 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253202
fixed issue 324522: KERNEL Handle leak from TimeTicks.WinRollover - add CloseHandle call for each thread handle
TBR=bruening@google.com
TEST=manual
BUG=324522

Review URL: https://codereview.chromium.org/177213012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253203 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253203