v.io/v23/rpc: silence CancelFunc leak checker in reflect_invoker_test

reflect_invoker_test.go creates some cancellable contexts that it
keeps fovever.  This change causes it also to keep the
corresponding context.CancalFunc values so the leak checker
doesn't complain about them being discarded before being called.

Change-Id: I7c5cae9eef3d523ff2a05677f0c5b84ba2f9b6b5
1 file changed