Jenkinsfile: run "make clean" in cleanup step
Jenkinsfile: run "make clean" in cleanup step

Signed-off-by: Sebastiaan van Stijn <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@gone.nl>

dims/docker,Ramzec/docker,paralin/docker,moby/moby,yongtang/docker,SvenDowideit/docker,Ramzec/docker,AkihiroSuda/docker,jameszhan/docker,estesp/docker,gnailuy/docker,flavio/docker,justincormack/docker,vdemeester/docker,thaJeztah/docker,yongtang/docker,ibuildthecloud/docker,thaJeztah/docker,thaJeztah/docker,nalind/docker,cpuguy83/docker,Ramzec/docker,ibuildthecloud/docker,flavio/docker,Ramzec/docker,moul/docker,bearstech/moby,konstruktoid/docker-1,yosifkit/docker,pradipd/moby,trebonian/docker,trebonian/docker,nalind/docker,djs55/docker,dims/docker,djs55/docker,Mokolea/docker,moby/moby,bearstech/moby,jimjag/docker,estesp/docker,jimjag/docker,mahak/docker,gnailuy/docker,docker/docker,AkihiroSuda/docker,bearstech/moby,nawawi/docker,paralin/docker,moul/docker,moby/moby,nalind/docker,moby/moby,gnailuy/docker,ibuildthecloud/docker,konstruktoid/docker-upstream,yosifkit/docker,jvanz/docker,bearstech/moby,Mokolea/docker,gnailuy/docker,SvenDowideit/docker,moul/docker,jthelin/docker,cpuguy83/docker,estesp/docker,trebonian/docker,ibuildthecloud/docker,djs55/docker,kolyshkin/moby,paralin/docker,kolyshkin/moby,thaJeztah/docker,justincormack/docker,vdemeester/docker,tmp6154/docker,nalind/docker,flavio/docker,pradipd/moby,Mokolea/docker,kojiromike/docker,yosifkit/docker,pradipd/moby,nawawi/docker,tmp6154/docker,kojiromike/docker,kojiromike/docker,mahak/docker,nawawi/docker,mahak/docker,konstruktoid/docker-upstream,jvanz/docker,ibuildthecloud/docker,jameszhan/docker,konstruktoid/docker-1,flavio/docker,docker/docker,docker/docker,yosifkit/docker,trebonian/docker,konstruktoid/docker-upstream,yongtang/docker,Mokolea/docker,konstruktoid/docker-1,konstruktoid/docker-upstream,nawawi/docker,AkihiroSuda/docker,paralin/docker,vdemeester/docker,jimjag/docker,justincormack/docker,moul/docker,kolyshkin/moby,dims/docker,jthelin/docker,cpuguy83/docker,jameszhan/docker,SvenDowideit/docker,jvanz/docker,tmp6154/docker,AkihiroSuda/docker,jimjag/docker,cpuguy83/docker,mahak/docker