go.mod: upgrade to golang-lru v0.5.4 (#20992)

golang-lru is now a go module, and the upgrade corrects a couple
of minor issues. In particular, the library could crash if you inserted
nil into an LRU cache.

go.mod

@@ -31,7 +31,7 @@ require (
 	github.com/google/go-cmp v0.3.1 // indirect
 	github.com/gorilla/websocket v1.4.1-0.20190629185528-ae1634f6a989
 	github.com/graph-gophers/graphql-go v0.0.0-20191115155744-f33e81362277
-	github.com/hashicorp/golang-lru v0.0.0-20160813221303-0a025b7e63ad
+	github.com/hashicorp/golang-lru v0.5.4
 	github.com/huin/goupnp v0.0.0-20161224104101-679507af18f3
 	github.com/influxdata/influxdb v1.2.3-0.20180221223340-01288bdb0883
 	github.com/jackpal/go-nat-pmp v1.0.2-0.20160603034137-1fa385a6f458

go.sum

@@ -93,8 +93,8 @@ github.com/gorilla/websocket v1.4.1-0.20190629185528-ae1634f6a989 h1:giknQ4mEuDF
 github.com/gorilla/websocket v1.4.1-0.20190629185528-ae1634f6a989/go.mod h1:E7qHFY5m1UJ88s3WnNqhKjPHQ0heANvMoAMk2YaljkQ=
 github.com/graph-gophers/graphql-go v0.0.0-20191115155744-f33e81362277 h1:E0whKxgp2ojts0FDgUA8dl62bmH0LxKanMoBr6MDTDM=
 github.com/graph-gophers/graphql-go v0.0.0-20191115155744-f33e81362277/go.mod h1:9CQHMSxwO4MprSdzoIEobiHpoLtHm77vfxsvsIN5Vuc=
-github.com/hashicorp/golang-lru v0.0.0-20160813221303-0a025b7e63ad h1:eMxs9EL0PvIGS9TTtxg4R+JxuPGav82J8rA+GFnY7po=
-github.com/hashicorp/golang-lru v0.0.0-20160813221303-0a025b7e63ad/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
+github.com/hashicorp/golang-lru v0.5.4 h1:YDjusn29QI/Das2iO9M0BHnIbxPeyuCHsjMW+lJfyTc=
+github.com/hashicorp/golang-lru v0.5.4/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
 github.com/hpcloud/tail v1.0.0 h1:nfCOvKYfkgYP8hkirhJocXT2+zOD8yUNjXaWfTlyFKI=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/huin/goupnp v0.0.0-20161224104101-679507af18f3 h1:DqD8eigqlUm0+znmx7zhL0xvTW3+e1jCekJMfBUADWI=