Remove runtime/references check from cpplint config.

Bug: webrtc:11630
Change-Id: I054b6b14b5784bfb5a44941595e2796031fc356e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/176328
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31393}

PRESUBMIT.py

diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 247b78e..199b726 100755
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -47,10 +47,13 @@
 # - build/c++11         : Rvalue ref checks are unreliable (false positives),
 #                         include file and feature blacklists are
 #                         google3-specific.
+# - runtime/references  : Mutable references are not banned by the Google
+#                         C++ style guide anymore (starting from May 2020).
 # - whitespace/operators: Same as above (doesn't seem sufficient to eliminate
 #                         all move-related errors).
 BLACKLIST_LINT_FILTERS = [
   '-build/c++11',
+  '-runtime/references',
   '-whitespace/operators',
 ]