Enable golint part of #14756

pkg/broadcastwriter
pkg/graphdb
pkg/httputils
pkg/ioutils

Signed-off-by: Lei Jitang <leijitang@huawei.com>

graphdb/conn_unsupported.go

@@ -2,6 +2,7 @@
 
 package graphdb
 
+// NewSqliteConn return a new sqlite connection.
 func NewSqliteConn(root string) (*Database, error) {
 	panic("Not implemented")
 }