clang-format: update buildtools path

Switch to the new checkout path.

BUG=chromium:930818
TEST=repo upload still works
CQ-DEPEND=CL:1491950

Change-Id: I493a287d98c474e28a8e0d4a4cfe964ab51a24e2
Reviewed-on: https://chromium-review.googlesource.com/1475867
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: LaMont Jones <lamontjones@chromium.org>
diff --git a/clang-format.py b/clang-format.py
index 8e884d4..84f9429 100755
--- a/clang-format.py
+++ b/clang-format.py
@@ -27,7 +27,7 @@
 # that have formatting errors are printed with this prefix.
 DIFF_MARKER_PREFIX = '+++ b/'
 
-BUILDTOOLS_PATH = os.path.join(constants.SOURCE_ROOT, 'chromium', 'src',
+BUILDTOOLS_PATH = os.path.join(constants.SOURCE_ROOT, 'src', 'chromium', 'src',
                                'buildtools')