update_engine: Disable SortIncludes in .clang-format

clang-format does simple alphabetical sorting of #include
lines, which conflicts with the fancier sorting used by
cpplint.py

BUG=none
TEST=repo upload

Change-Id: Ia053a932f08f38e18a1855302de5b36c80aeb7e5
Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/system/update_engine/+/2153586
Tested-by: Jae Hoon Kim <kimjae@chromium.org>
Commit-Queue: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
Auto-Submit: Jae Hoon Kim <kimjae@chromium.org>
diff --git a/.clang-format b/.clang-format
index c1244fe..aed0ce8 100644
--- a/.clang-format
+++ b/.clang-format
@@ -36,3 +36,7 @@
 DerivePointerAlignment: false
 PointerAlignment: Left
 TabWidth: 2
+
+# cpplint.py does smarter #include sorting than clang-format (the former ignores
+# case and changes '-' to '_').
+SortIncludes: false