cleanup: convert some more uses of NULL to nullptr (#2359)
cleanup: convert some more uses of NULL to nullptr (#2359)

Signed-off-by: Mike Schore <270e364e708f2af319f244c09ceba52a03dbd980@gmail.com>
envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile