Add a cpplint preupload hook.

This runs cpplint.py over modified .cc and .h files before uploading
them to gerrit. This generally takes ~1-2 seconds based on my testing
and the longest one I've been able to find was ~10 seconds.

Test: PREUPLOAD_COMMIT=d9911eeca ./tools/cpplint_presubmit.py
Test: PREUPLOAD_COMMIT=405284789 ./tools/cpplint_presubmit.py
Test: PREUPLOAD_COMMIT=9763f2eb7 ./tools/cpplint_presubmit.py
Test: Manual

Bug: 35810246
Bug: 36855589

Change-Id: Ie0ed9136bdde15d78f2aa40c73fef97e12d12dda
diff --git a/PREUPLOAD.cfg b/PREUPLOAD.cfg
index cf1832b..0ed230c 100644
--- a/PREUPLOAD.cfg
+++ b/PREUPLOAD.cfg
@@ -1,2 +1,3 @@
 [Hook Scripts]
 check_generated_files_up_to_date = tools/cpp-define-generator/presubmit-check-files-up-to-date
+check_cpplint_on_changed_files = tools/cpplint_presubmit.py