Fix runtests.py to work on platforms without multiprocessing.Pool()
Fix runtests.py to work on platforms without multiprocessing.Pool()

aep/clay,jckarter/clay,aep/clay,jckarter/clay,jckarter/clay,iamrekcah/clay,mario-campos/clay,aep/clay,jckarter/clay,mario-campos/clay,iamrekcah/clay,iamrekcah/clay,aep/clay,iamrekcah/clay,jckarter/clay,iamrekcah/clay,mario-campos/clay,mario-campos/clay,jckarter/clay,aep/clay,aep/clay,mario-campos/clay