Don't check header guards in cpplint.py

Header guards are checked by CheckForIncludeGuards which has broader
coverage than cpplint.py and should therefore be preferred.

Having two include-guard checkers that cover different sets of files and
use different tags to silence warnings is just confusing.

Bug: 1309977
Change-Id: Ic0d1ad610cf9c34d6777d852da2e2e22b8686552
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3587725
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>

presubmit_canned_checks.py

@@ -40,10 +40,12 @@ OFF_BY_DEFAULT_LINT_FILTERS = [
 # Justifications for each filter:
 # - build/c++11         : Include file and feature blocklists are
 #                         google3-specific
+# - build/header_guard  : Checked by CheckForIncludeGuards
 # - runtime/references  : No longer banned by Google style guide
 # - whitespace/...      : Most whitespace issues handled by clang-format
 OFF_UNLESS_MANUALLY_ENABLED_LINT_FILTERS = [
     '-build/c++11',
+    '-build/header_guard',
     '-runtime/references',
     '-whitespace/braces',
     '-whitespace/comma',