Dockerfile: also build old registry on armhf
Dockerfile: also build old registry on armhf

Building the old version of the registry is not supported
on arm64, but building on armhf is possible.

Before using a multi-arch Dockerfile, the registry was
built on armhf as well, but this got lost in the transition
in commit f1701a741d77a92d28138944193e23aabfc74abe.

This commit re-enables building the old registry on armhf.

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

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