Fix building with Go 1.10

stevenroose · stevenroose · commit 31ffdb3b0e0b · 2018-03-01T09:51:46.000+01:00
diff --git a/cmd/geth/usage.go b/cmd/geth/usage.go
@@ -22,8 +22,6 @@ import (
 	"io"
 	"sort"
 
-	"strings"
-
 	"github.com/ethereum/go-ethereum/cmd/utils"
 	"github.com/ethereum/go-ethereum/internal/debug"
 	"gopkg.in/urfave/cli.v1"
