basehub: Avoid race conditions with concurrent calls to unhandle_port
basehub: Avoid race conditions with concurrent calls to unhandle_port

Change-Id: I790d525e3daa63438bfbff7820c2de9203ad8139

Kurento/kms-elements,Kurento/kms-elements,TribeMedia/kms-elements,shelsonjava/kms-elements,shelsonjava/kms-elements,shelsonjava/kms-elements,TribeMedia/kms-elements,Kurento/kms-elements,TribeMedia/kms-elements