[cpplint] Disable runtime/references lint

Google Style Guide now prefers references to pointers because references
are non-nullable.

See https://google.github.io/styleguide/cppguide.html#Inputs_and_Outputs which now says:

> Non-optional input parameters should usually be values or const references, while non-optional
> output and input/output parameters should usually be references (which cannot be null).

This means runtime/references lint is outdated and can be disabled.

R=kustermann@google.com

Change-Id: Idec650603982387c000671aad7d77727a008f5cd
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/279388
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>

runtime/CPPLINT.cfg

@@ -7,4 +7,7 @@ set noparent
 #
 # Do not complain about whitespace. That is handled
 # by the clang format presubmit check.
-filter=-readability/fn_size,-whitespace/indent
+#
+# Do not complain about non-const references. Chromium and Google code
+# styles now recommend references instead of pointers.
+filter=-readability/fn_size,-whitespace/indent,-runtime/references